in the past on x86 & macppc i've found that mplayer uses much less
cpu than both xine or ogle.  i think mplayer also has ultrasparc
assembler code that isn't enabled by default on netbsd/sparc64.

are you playing full screen?  if so, does it work non-fullscreen?
is "Xvideo" extension available for you?  (what does "xvinfo" say)


.mrg.