1.
verifique,
Tools => Preferences => Show All => Video => Disable screensaver
sevocêquiserativaraproteçãodetela,desmarque-a.
Tools=>Preferences=>ShowAll=>Advanced=>Inhibitthepowermanagementdaemonduringplayback
2.
experimente este script para as respectivas opções
#!/bin/bash
xset -dpms #do not allow turn off
xset s off #do not allow screen saver
xset dpms #Allow turn off if not work then try -dpms
xset s on #Allow screen saver
exit