mpeg files are *much* bigger than divx (avi) files and they are designed for use with dvd players (vcd/svcd).
convert them to divx easily and play on gpcinema.
It wouldnt be worth having an MPEG player for the gamepark. MPEGs usually use like 10MB per 1 minutes of video(depending on bitrate/quality). So at most you'd have like 12 minutes on a 128MB SMC so whats the point? Unless you just really want to watch two 6 minute music videos =) Weird Al videos maybe........