iPod accepts only MP4 format video, If your video is MP4 video, just open iTunes and click "File" to add your videos music to iTunes library. then plug in your iPod to computer, iTunes will detect your iPod as a device. select your iPod device on the left panel of iTunes, click "Movies"("Music") tab, check the videos(Music)you want to sync and click "Apply", done.
If your video isn't MP4 format, you need third party software to convert video to MP4, I always use Aimersoft iPod Converter Suite, it can easily convert dvd video to ipod with quite fast conversion speed and excellent output quality, that's really good for me, you can free download it here:
http://www.aimersoft.com/ipod-converter-suite. html