How to recreate the problem: 1. put your firefox in fullscreen mode (use the F11 key). 2. navigate to any html5 video (on vimeo or anywhere). 3. click the video's fullscreen button (now the video is in fullscreen too). 4. THE PROBLEM: If the video stops or ESC is pressed or the video's exit fullscreen button clicked, we don't return to the fullscreen firefox but firefox goes to windowed mode. Firefox should stay in fullscreen mode after a fullscreen html5 video just like with any flash based video. Firefox version: 36.0.4 Os: win7