Here's what I found out (I also have a G2). The Canon does not create a "true" AVI video. It is a derivative called "motion-AVI". I don't know much about this format, although most desktop players that handle AVI will play both formats just fine.
That being said, there is only one PPC program that I know of that will play "motion-AVI" files.
PQView
http://www.bitbanksoftware.com/PQV.html
I've seen it for myself - I was able to pop out the CF card from my camera, pop it into my Axim, and play the movie right away. It shows up as "MVI_0581.AVI" and it was a 7mb file. I left it on the CF card, put the card back in the camera, and was able to upload it to my desktop PC later that day.
Here's a Pocket PC Magazine review.