I have a Firefox playing videos (HTML5 video tag) on some screens for advertising purpose. There is some autoit script that switches off the screen during the night. The customer requrement is that the videos should be played even with the screen switched off (Sounds weird but yes...). Recently I updated the Firefox version from 32 to 39 and it turned out that Firefox 39 stops to play anything while screen ist switched off. No Javascript timeout or a meta-refresh tag do anything to reload a page. I tested the current version (43 at the time of this writing) too without success. Does anybody know if there is some preference/setting/config to force Firefox to work even if the screen is off? (This is a question i posted on stackoverflow too: http://stackoverflow.com/questions/38660819/how-to-force-firefox-to-play-video-while-screen-is-switched-off)