Are you sure it had no video stream or you just couldn't play it? Did you try it with VLC player? The size of the file should help indicate wether there's a video stream.

Personally, most of the music videos I tried out with iTunes were mpeg & there was no issue importing them. So they must have been mpeg 4. But with mpeg you don't know whether you're getting mpeg 1, 2 or 4. It saves the issue of converting them.