If you have videos on your iPod, you want to access them from the Video menu. At the main menu on your iPod, you should see (depending on which settings you actually have turned on) Music, Photos, Videos, etc. If you don't see Video in your main menu, go into Settings, Main Menu and turn Video on so that it shows up in you main menu. Play the video from there. If you access a video through the album, artist or other menus, it will just show album artwork and play the audio, like any other song file.