Steps to reproduce: * Install aboutmedia addon * Scroll through Facebook past a number of videos * Look at the video elements in F10 -> Tools -> Page Info on the Media tab * Look at the video elements in about:media Expected results: Only the videos in Page Info should be running. Others should be shut down. Actual results: Most of the videos in about:media have active decoders even though they don't appear in the page info. Note: I'm not sure why these videos aren't shut down by the dormant mode timer.

about:media shows the media element on a page; are you sure the decoder aren't shutdown ?

this is what's showing on about:media after leaving the facebook page idle for 1 minute: https://video-syd1-1.xx.fbcdn.net/v/t42.1790-2/12689932_642426669238780_949368584_n.mp4?efg=eyJybHIiOjQ2OCwicmxhIjo2MjYsInZlbmNvZGVfdGFnIjoidjNfNDI2X2NyZl8yM19tYWluXzMuMF9zZCJ9&rl=468&vabr=260&oh=02b94e0673178e3680979c38fa7c3b47&oe=578DD891 currentTime: 0 Quality: 100% (total:12 dropped:0 corrupted:0) Buffered ranges: [(0, 19.111429)] Internal Data: audio decoder: shutdown audio frames decoded: 1 audio state: ni=0 no=0 ie=0 demuxr:0 demuxq:0 decoder:0 tt:-1.000000 tths:-1 in:0 out:0 qs=0 pending:0 waiting:0 sid:4294967295 video decoder: shutdown hardware video decoding: disabled video frames decoded: 1 (skipped:0) video state: ni=0 no=0 ie=0 demuxr:0 demuxq:0 decoder:0 tt:-1.000000 tths:-1 in:0 out:0 qs=0 pending:0 waiting:0 sid:4294967295 note the: "video decoder: shutdown" this indicates that there are none running at present. it will be recreated the next time we need a frame decoded