As discussed in another thread, electricsheep needs to add the option:
to its mplayer command-line arguments in Linux (alternatively, users can add stop-xscreensaver = no to their ~/.mplayer/config file, but it would be preferable to not set this option for all mplayer instances).
A recent mplayer bug prevented this option from doing anything. However, that bug has been fixed.
This fix will allow monitors to fall to sleep (via DPMS) while running electricsheep.