DVD's don't play on my G3 iMac

I'm trying to get a short video clip into my G3 400 MHz iMac. The camera's USB port works, but the file is .avi. I was hoping to get something that I could import to iMovie by putting it on a DVD first.

I burned a DVD on our Insignia 1001 player/recorder, but the iMac spits it out, with no message.

I tried playing a pre-recorded DVD, but the only thing that plays is the intro. Error message if "Play" is pushed.

I remember watching a bug cartoon DVD movie on the machine when I first got it.