I have Auto play disabled, along with all options to disable Auto play even when sound is off! I understand Mozilla chose not to block all auto play videos and they have there reasons for that. I have tweaked a few settings in about:config, I cannot remember which ones though. My issue is with some websites, YouTube being the main one I use. When I open a channels page sometimes the intro to there page Auto plays with sound. If I open the page in a new tab auto play will not happen. I have just checked.. Autoplay is not disabled if I am currently viewing a YouTube page and open a video. So obviously YouTube is recognizing I am viewing the current page and is overriding any setting I have. YouTube will not auto-play any other videos only these intro videos on users home channel page. I cannot seem to block YouTube videos Auto-playing on my android phone with Firefox, however that is a whole different issue. What I want is a global option where I can stop ALL videos from Auto-playing until I press a play button. I know I am not alone in wanting this.