When I am browsing facebook, if I watch a video from within facebook in one of the in-tab windows that form, then I move onto something else. If I go to share something or click on something that opens another in-tab window, the audio from old videos that I have watched will start to play again, sometimes from multiple videos at a time, and often they will not stop without restarting firefox. Which is annoying because if I restart, then I will lose my scroll location on facebook.