how to play AVI file on Thrive?

I've got an AVI file that won't play on my wife's Thrive. I have it on a thumb drive. the device shows the file there but when I try to play it, I get an error.

i figure my choices are

1) try to find an app that will play AVI?

2) convert the file to another format

3) any other ideas?

what would y'all suggest here?

thanks
gary in vermont