iTunes is totally a freeware provided by Apple to help you load your movies, music, TV show, podcast onto iPod.
But since iPod only support MP4, M4V formats, I think you may need software to convert videos. I prefer to use Aimersoft iPod Converter Suite for conversion of either DVDs or videos on your computer. You can find its step-by-step guide on:
Hope it helps.
Just connect ipod to your computer, open iTunes, drag and drop the photos and videos to iTunes. Sometimes you need to make sure the video file is the right format (.mp4).
Use a video converter: