Using the GSpot AVI analysis I find that (Xvid ISO MPEG4, Xvid 1.0.3, Xvid 1.1.2 final, FMP4 ffdshow ISO MPEG4) will play fine.
I have been encoding videos with AutoGK (XviD 1.0.3-20122004_Final Release_,none play in Geosat microHD. Are you saying you have XviD material that plays?
Btw, the specs say it plays Xvid. http://satelliteav.com/p/shop/?ws_pid=1593&ws_cat=446