.*audio)(\[(?.*)\])?(?(.*)?)$' ) {
                                                    If( $matches.audioparam) {
                                                        $NewFormatElem= '{0}[format_id*={1},{2}]{3}' -f $matches.Pre, $ThisLanguage, $matches.audioparam, $matches.post
                                                    }
                                                    Else {
                                                        $NewFormatElem= '{0}[format_id*={1}]{2}' -f $matches.Pre, $ThisLanguage, $matches.post
                                                    }
                                                }
                                                Else {
                                                    $NewFormatElem= $Elem
                                                    Write-Warning ('Problem determining where to add language criteria in {0}, leaving criteria as-is' -f $Elem)
                                                }
                                                $null= $NewFormat.Add( $NewFormatElem)
                                            }

                                            # With language filters determined, recreate filter and add whole non-language specific qualifiers as next best 
                                            $ThisFormat= ($NewFormat -Join ','), $ThisFormat -Join ','

                                        }
                                        Else {
                                            # Only 1 Language available, so use default audio stream
                                            Write-Warning ('Only single audio stream available, will use default audio stream')
                                        }
                                    }
                                    Else {
                                        # No multiple audio languages, use default audio stream
                                        Write-Warning ('Multiple audio streams not available, will use default audio stream')
                                    }
                                    $Arg += ('--format {0}' -f $ThisFormat)
                                }
                                Else {
                                    # Check for embedded YouTube 
                                    If( $OnDemandPage -match '"https:\/\/www\.youtube-nocookie\.com\/embed\/(?.+?)\?enablejsapi=1&"') {
                                        $Endpoint= 'https://www.youtube.com/watch?v={0}' -f $matches.YouTubeID
                                        Write-Verbose ('Using YouTube URL {0}' -f $Endpoint)
                                        $Arg = @( ('-o "{0}"' -f ($vidFullFile -replace '%', '%%')), $Endpoint)
                                        $Arg += ('--concurrent-fragments {0}' -f $ConcurrentFragments)
                                        If ( $Format) { $Arg += ('--format {0}' -f $Format) } Else { $Arg += ('--format 22') }
                                        If ( $Subs) { $Arg += ('--sub-lang {0}' -f ($Subs -Join ',')), ('--write-sub'), ('--write-auto-sub'), ('--convert-subs srt') }
                                    }
                                    Else {
                                        Write-Warning "Skipping: Embedded AMS or YouTube URL not found"
                                        $EndPoint= $null
                                    }
                                }

                            }
                            Else {
                                 Write-Warning ('Skipping: {0} unavailable' -f $downloadLink)
                            }
                        }
                        Else {
                            # Direct
                            Write-Verbose ('Using direct video link {0}' -f $downloadLink)
                            If( $downloadLink) {
                                $Endpoint= $downloadLink
                                $Arg = @( ('-o "{0}"' -f $vidFullFile), $downloadLink)
                            }
                            Else {
                                Write-Warning ('No video link for {0}' -f ($SessionToGet.Title))
                                $Endpoint= $null
                            }
                        }
                        If( $Endpoint) {
                            # Direct, AMS or YT video found, attempt download but first define common parameters

                            If ( $ProxyURL) { 
                                $Arg += ('--proxy "{0}"' -f $ProxyURL)
                            }
                            $Arg+= '--socket-timeout 90'
                            $Arg+= '--no-check-certificate'                            
                            $Arg+= '--retries 15'
                            $Arg+= '--concurrent-fragments {0}' -f $ConcurrentFragments

                            If ( $Subs) { $Arg += ('--sub-lang {0}' -f ($Subs -Join ',')), ('--write-sub'), ('--write-auto-sub'), ('--convert-subs srt') }

                            Write-Verbose ('Running: {0} {1}' -f $YouTubeEXE, ($Arg -join ' '))
                            Add-BackgroundDownloadJob -Type 2 -FilePath $YouTubeDL -ArgumentList $Arg -File $vidFullFile -Timestamp $SessionTime -scheduleCode ($SessionToGet.sessioncode) -Title ($SessionToGet.Title)
                        }
                        Else {
                            # Video not available or no link found
                            $VideoInfo[ $InfoPlaceholder]++
                        }
                    }

                    If( $Captions) {
                        $captionExtFile= $vidFullFile -replace '.mp4', ('.{0}' -f $CaptionExt)

                        If ((Test-ResolvedPath -Path $captionExtFile) -and -not $Overwrite) {
                            Write-Host ('Caption file exists {0}' -f $captionExtFile) -ForegroundColor Gray
                        }
                        Else {
                            # Caption file in AMS needs seperate download, fetch onDemand page if not already downloaded for video
                            If(! $OnDemandPage) {
                                If( $SessionToGet.onDemand) {
                                    Try {
                            		Write-Host ('Fetching video page to retrieve transcript information from {0}' -f $SessionToGet.onDemand) 
                                        $DownloadedPage= Invoke-WebRequest -Uri $SessionToGet.onDemand -Proxy $ProxyURL -DisableKeepAlive -ErrorAction SilentlyContinue
                                        If( $DownloadedPage) {                        
                                            $OnDemandPage= $DownloadedPage.RawContent 
                                        }
                                    }
                                    Catch {
                                        #Problem retrieving file, look for alternative options
                                    }
                                }
                              
                            }
                            # Check for vtt files before we check any direct caption file (likely docx now)
                            $captionFileLink= $Null
                            If( $OnDemandPage -match 'captionsConfiguration = (?{.*});') {
                                $CaptionConfig= ($matches.CaptionsJSON | ConvertFrom-Json).languageList
                                If( $Subs) {
                                    $captionFileLink= ($CaptionConfig | Where-Object {$_.srclang -eq $Subs}).src
                                }
                                If(! $captionFileLink) {
                                    $captionFileLink= ($CaptionConfig | Where-Object {$_.srclang -eq 'en'}).src
                                }
                            }
                            If( ! $CaptionFileLink) {
                                $captionFileLink= $SessionToGet.captionFileLink
                            }
                            If( ! $captionFileLink) {

                                If(! $OnDemandPage) {
                                    # Try if there is caption file reference on page
                                    Try {
                                        $DownloadedPage= Invoke-WebRequest -Uri $downloadLink -Proxy $ProxyURL -DisableKeepAlive -ErrorAction SilentlyContinue
                                        $OnDemandPage= $DownloadedPage.RawContent
                                    }
                                    Catch {
                                        $DownloadedPage= $null
                                        $onDemandPage= $null
                                    } 
                                }
                                Else {
                                    # Reuse one from video download
                                }

                                If( $OnDemandPage -match '"(?https:\/\/mediusprodstatic\.studios\.ms\/asset-[a-z0-9\-]+\/transcript\{0}\?.*?)"' -f $CaptionExt) {
                                    $captionFileLink= $matches.AzureCaptionURL
                                }
                                If( ! $captionFileLink) {
                                    $captionFileLink= $captionURL -f $SessionToGet.SessionCode
                                }
                            }
                            If( $captionFileLink) {
                                Write-Verbose ('Retrieving caption file from URL {0}' -f $captionFileLink)

                                 $captionFullFile= $captionExtFile
                                 Write-Verbose ('Downloading {0} to {1}' -f $captionFileLink,  $captionFullFile)
                                 Add-BackgroundDownloadJob -Type 3 -FilePath $captionExtFile -DownloadUrl $captionFileLink -File $captionFullFile -Timestamp $SessionTime -scheduleCode ($SessionToGet.sessioncode) -Title ($SessionToGet.Title)

                             }
                             Else {
                                 Write-Warning "Subtitles requested, but no Caption URL found"
                             }
                        }
                    }
                    $OnDemandPage= $null
                }
              }

              If(! $NoSlidedecks) {
                If ( !( [string]::IsNullOrEmpty( $SessionToGet.slideDeck)) ) {
                    $downloadLink = $SessionToGet.slideDeck
                }
                Else {
                    If( $NoGuessing) {
                        $downloadLink= $null
                    }
                    Else {
                        # Try alternative construction
                        $downloadLink = $SlidedeckUrl -f $SessionToGet.SessionCode
                    }
                }

                If ($downloadLink -match "view.officeapps.live.com.*PPTX" -or $downloadLink -match 'downloaddocument' -or $downloadLink -match 'medius' -or $downloadLink -match 'confirmation\.aspx') {

                    $DownloadURL = [System.Web.HttpUtility]::UrlDecode( $downloadLink )
                    Try {
                       If( $downloadLink -notmatch 'confirmation\.aspx') {
                           $ValidUrl= Invoke-WebRequest -Uri $DownloadURL -Method HEAD -UseBasicParsing -DisableKeepAlive -MaximumRedirection 10 -ErrorAction SilentlyContinue
                       }
                       Else {
                           $ValidUrl= Invoke-WebRequest -Uri $DownloadURL -Method GET -UseBasicParsing -DisableKeepAlive -MaximumRedirection 10 -ErrorAction SilentlyContinue
                       }
                    }
                    Catch {
                        $ValidUrl= $false
                    }

                    If( $downloadLink -match 'confirmation\.aspx' -and $ValidURL.Headers.'Content-Type' -ilike 'text/html') {
                        # Extra parsing for MS downloads
                        If( $ValidUrl.RawContent -match 'href="(?https:\/\/download\.microsoft\.com\/download[\/0-9\-]*\/.*(pdf|pptx))".*click here to download manually') {
                            $DownloadURL= [System.Web.HttpUtility]::UrlDecode( $Matches.Url)
                            $ValidUrl= Invoke-WebRequest -Uri $DownloadURL -Method HEAD -UseBasicParsing -DisableKeepAlive -MaximumRedirection 10 -ErrorAction SilentlyContinue
                        }
                    }

                    If( $ValidUrl ) {
                        If( $DownloadURL -like '*.pdf' -or $ValidURL.Headers.'Content-Type' -ieq 'application/pdf') {
                            # Slidedeck offered is PDF format
                            $slidedeckFile = '{0}.pdf' -f $FileName
                        }
                        Else {
                            $slidedeckFile = '{0}.pptx' -f $FileName
                        }
                        $slidedeckFullFile =  '\\?\{0}' -f (Join-Path $DownloadFolder $slidedeckFile)
                        if ((Test-ResolvedPath -Path $slidedeckFullFile) -and ((Get-ChildItem -LiteralPath $slidedeckFullFile -ErrorAction SilentlyContinue).Length -gt 0) -and -not $Overwrite) {
                            Write-Host ('Slidedeck exists {0}' -f $slidedeckFile) -ForegroundColor Gray 
                            $DeckInfo[ $InfoExist]++
                        }
                        Else {
                            Write-Verbose ('Downloading {0} to {1}' -f $DownloadURL,  $slidedeckFullFile)
                            Add-BackgroundDownloadJob -Type 1 -FilePath $slidedeckFullFile -DownloadUrl $DownloadURL -File $slidedeckFullFile -Timestamp $SessionTime -scheduleCode ($SessionToGet.sessioncode) -Title ($SessionToGet.Title)
                        }
                    }
                    Else {
                        Write-Warning ('Skipping: Slidedeck unavailable {0}' -f $DownloadURL)
                        $DeckInfo[ $InfoPlaceholder]++
                    }
                }
                Else {
                    Write-Warning ('No slidedeck link for {0}' -f ($SessionToGet.Title))
                }
              }
            }

            $JobsRunning= Get-BackgroundDownloadJobs

            if ([system.console]::KeyAvailable) { 
                $key = [system.console]::readkey($true)
                if (($key.modifiers -band [consolemodifiers]"control") -and ($key.key -eq "C")) {
                    Write-Host "TERMINATING" -ForegroundColor Red
                    Stop-BackgroundDownloadJobs
                    Exit -1
                }
            }
                   
        }

        $ProcessedSessions= $i

        Write-Progress -Id 1 -Completed -Activity "Finished processing session information"

        $JobsRunning= Get-BackgroundDownloadJobs
        If ( $JobsRunning -gt 0) {
            Write-Host ('Waiting for download jobs to finish - press Ctrl-C once to abort)' -f $JobsRunning)
            While  ( $JobsRunning -gt 0) {
                if ([system.console]::KeyAvailable) { 
                    Start-Sleep 1
                    $key = [system.console]::readkey($true)
                    if (($key.modifiers -band [consolemodifiers]"control") -and ($key.key -eq "C")) {
                        Write-Host "TERMINATING" -ForegroundColor Red
                        Stop-BackgroundDownloadJobs
                        Exit -1
                    }
                }
                Start-Sleep 5
                $JobsRunning= Get-BackgroundDownloadJobs
            }
        }
        Else {
            Write-Host ('Background download jobs have finished' -f $JobsRunning)
        }

        Write-Progress -Id 2 -Completed -Activity "Download jobs finished"  

        Write-Host ('Selected {0} sessions out of a total of {1}' -f $ProcessedSessions, $TotalNumberOfSessions)
        Write-Host ('Downloaded {0} slide decks and {1} videos.' -f $DeckInfo[ $InfoDownload], $VideoInfo[ $InfoDownload])
        Write-Host ('Not (yet) available: {0} slide decks and {1} videos' -f $DeckInfo[ $InfoPlaceholder], $VideoInfo[ $InfoPlaceholder])
        Write-Host ('Skipped {0} slide decks and {1} videos as they were already downloaded.' -f $DeckInfo[ $InfoExist], $VideoInfo[ $InfoExist])
    }