Comment 134 for bug 434476

Doesn't seem to be fixed in Firefox 33 on OpenSuse 13.1 with KDE4 & XScreenSaver-5.29 (not KDE's one): xscreensaver still sprungs up while playing fullscreen video on Youtube. May be a result of using "Download Manager (S3)" addon which draws a bar at the bottom that disappear slightly after video goes fullscreen. One more reason why it should work on non-fullscreen videos also, since the definition of "fullscreen" seems ambiguous.

Also, how about inhibiting screensaver on flash plugin spawn and uninhibiting on its termination ? Adobe will never add this functionality, but we are stuck with it. Doing so in Firefox as extension of this patch looks like the most straightforward solution. Especially in comparison to something like https://github.com/iye/lightsOn