Seems like mplayer doesn't like xvid4 encoded movies - when using default settings, it crashes right away; when forcing mplayer -vc +xvid I do get an image, but a corrupt one (you can tell what it's supposed to show, but it has four images overlapping, striped and squished together).
I fetched the sources for mplayer 1.0pre7try2 and built it to check, and surprisingly enough it detected and played the xvid right away
my build is of no use because of some colour conversion issue (seems like orange and blue are being switched. Funky effect) but I just thought I'd mention it.
Oh, and btw... it was compiled with gcc, and it's SLOW
I really ought to get me MIPSPro.