For mplayer issue you might find this tread helpful http://bbs.archlinux.org/viewtopic.php?id=60110
You can also try out different video_out (vo) drivers, to see which one works best. To get the list of avalible video out drivers; mplayer -vo help.

bandito

 Video (mplayer) in fullscreen is choppy and slow.  Complaints of my hardware
   being too slow etc.