If you have Raspberry PI and decide to use it media center,you will probably look for Raspberry PI ready player.
omxplayer is tool for you
#aptitude install omxplayer xterm
to start using it, right click on desired video->open with->and enter below for custom command
xterm -fullscreen -fg black -bg black -e omxplayer -o hdmi -r %f
to get it running in full screen mode.