You need to update the ipod firmware if its not already done. And sometimes music videos wont show up in the music video section, most stuff just goes to the movies section.
If you'v put them on the music videos section on itunes, they wont show anywhere on the ipod, its all to do with how its coded and shit.
If you want more videos for it aswell, go to
www.videoseed.com or
www.podtropolis.com
Shits ill. But its torrents and that, cant remember whether you can use em.