While movie players (such as VLC) prevent the GNOME screensaver from activating during movie playback, playing Flash videos does not affect the screensaver, which means having to move the mouse occasionally, or turning off the screensaver while watching YouTube videos and the like.
There is no perfect solution to this, but using a script, it is possible . . . → Read More: Prevent GNOME screensaver during full-screen Flash videos
