javascript:(function() {
 /* Config variable - 1 to oepn in new tab, 0 to not.     */
 var openInNewTabWatchRandomVideo = 1;

 /* Class name of element holding link for video.         */
 var videoFeedWatchRandomVideo = /* HOT-GLUE - may change */
  document.getElementsByClassName("yt-lockup-view-model__content-image");

 /* Length of all videos in home feed. */
 var videoFeedWatchRandomVideoLen = videoFeedWatchRandomVideo.length;

 /* Generate random value using length. */
 var randomValWatchRandomVideo = 
  Math.floor(Math.random() * videoFeedWatchRandomVideoLen);

 /******************************************************************************************
  MAIN FUNCTION
  ******************************************************************************************/
 function watchRandomVideo(target) {
  /* Make sure video links are loaded.                                               */
  if (videoFeedWatchRandomVideo.length >= 1 && /* at least one loaded                */
      videoFeedWatchRandomVideo[0].hasAttribute("href") /* good guess load correctly */
     ) {
   /* get video link                                                                 */
   let videoURL = 
     videoFeedWatchRandomVideo[randomValWatchRandomVideo].href;

   /* watch random video                                                             */
   window.open(videoURL, target);
  } else {
   /* do nothing                                                                     */
   let skip;
  }
 }

 /* Check if configured to open in new tab.                                          */
 if (openInNewTabWatchRandomVideo == 1) {
  /* if so, open in new tab                                                          */
  watchRandomVideo("_blank");
 } else {
  /* if not, open in current window                                                  */ 
  watchRandomVideo("_self");
 }
})();