iPod supports only mp4 and h.264 video, you have to convert your video to iPod compatible video in advanced, then add the converted mp4 video to iTunes library, plug in your iPod to computer, sync your iPod with iTunes, that's all. If you need detailed info, here is a step by step guide will teach you how to put DVD and video to iPod
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You can get useful information by visiting Apple official site: http://www.apple.com
Contact me if you have any other question.