Only when I reload the site the autoplay icon appears and the video is prevented from being played (This works only in like 80% of the cases). The same for Channel Trailers (I really hate Youtube for inventing these). Opening a video in a new tab works fine and it's waiting until I decide to play it. Setting ''media.autoplay.blocking_policy = 2'' in about:config didn't help. Autoplay is set to block audio and video everywhere.