I'm using Ubuntu 11.10.
There's a option in Totem that says to disable screen saver while playing movie, but it doesn't work.
Is there anything else I can do to make it work ?
You can alternatively use Caffeine
Its a status bar application able to temporarily prevent the activation of both the screensaver and the "sleep" powersaving mode
You can get Caffeine here https://launchpad.net/caffeine or
sudo add-apt-repository ppa:caffeine-developers/ppa sudo apt-get update sudo apt-get install caffeine python-glade2