Right... Firstly, to avoid confusions further, there's 3 players out there - the first one was Zardoz's GpDivx which suposedly doesn't have sound. Actually, it does, but you have to encode uncompressed and at the lowest quality possible (1kbs/8Kbit mono). It also has massive fluctuations in framerate, although on a good day, it's a LOT better than either of the other two (15-20fps ish, but at awkward bits it drops to 8). Unfortunately, that means its very hard to get a constant rate out of it. Which is annoying.
Secondly, there is Moviepark. You've got to buy it, but its a great piece of software. Plays stuff at 10fps and no more
and 22KHz sound MP3, or something like that. But with a bit of work, the stuff playing on it looks fine, and decimation stops too much jutteryness. I think it's got a filesize limit of 30 megs, but since its also got a file selector, that's no problem.
Finally, and most recently, there's GPMP, which is supposed to be a demo. This means several things - firstly, no file selector, which is all well and good because we can rename whatever to GundamOP.avi . Secondly, and far far more frustratingly, its got a maximum file length of 6minutes 30 seconds, so its OK for music vids, but for a movie, you have to split it into ludicrously small chunks and then use GPFM to move them about a lot.
Now that everyone knows what all the players ARE, how to encode for GPMP was the question was it not? Well, I was just breaking by teeth on Virtualdub at the time, so I used kind of bad methods, but everything works when you were using quality based encoding - although the quality had to be ludicrously low in order to get a decent file-size. I'm guessing Atrkid's moviepark encoding guide on faqs.gp32emu.com would help you though, since I managed to play quite a few moviepark files on it. Only thing is - don't use 2 pass encoding on it. Just crashes and is frustrating. Also, you can use a framerate of roughly up to 15fps if you want to - so its slightly less juttery. More importantly, you don't have to decimate a movie at 12.5fps down to just over 6fps in order to stop misalignment; you can just leave it alone
.
But imho, whilst I worked with GPMP for quite some time, moviepark is quite a bit better. On account of it being too annoying to move about sections of a film every 5 minutes grrr.