Okay, just a bit more confusion.

I have Nero 7 now. I've used it to burn avi movies to DVD's three times.
One time the video worked in my DVD player and it looked excellent. The other two times, I got an error message on my DVD player saying that this disc might not have a playback option.

I did all three exactly the same way, and they were all avi files.

Now I'm gonna pull my hair out!!