Q: Hi! I have an iPod Touch 2nd Generation videos in iTunes won't copy?

Hello! I have an iPod Touch 2nd Generation, and I've been trying to put some videos on it, but whenever I try to sync it with my videos on iTunes, I get a message that says ''__' Was Not Copied to the iPod "__'s iPod because it cannot be played on this iPod'. Any help out there? I've tried exporting the file from QuickTime as the iPod/iPhone version, but it still won't play on my iTouch when i sync it from iTunes. I would try using a third party video converter to make it hte correct format for this old iTouch, but I don't even know what the correct format is! The software version is 4.2.1. Any ideas? Thanks in advance!