When full-screen viewing a video on youtube, firefox will helpfully pop up a notice about how youtube is now full screen and would you like to allow or deny that. However, at this point the view is _already_ full screen, and there is no way to interact with the actual video until either "allow" or "deny" is clicked, even if the volume at which the video is playing is literally enough to blow up a medium sized Deathstar, and the user REALLY needs to be able to control the video player. It would be so fantastic if this overlay wasn't UI block, but just faded out if the user doesn't click "deny" for a few seconds. We know it's full screen, because that's what Firefox has already allowed to happen.