From The Neuros Technology Wiki
Using iTunes to put video on the iPod
iTunes is the officially designated software for most iPod operations. With it, you can organize your media, purchase music and videos, and transfer the files to your iPod. It's simple, it has a snazzy interface, and it does almost everything for you. iTunes doesn't provide video-encoding features, but it does offer a relatively large online music and video store, where you can purchase various pre-formatted videos for varying fees, usually $2.99. You can also, and unless you've set up third-party software, you'll probably need to use iTunes to transfer any other videos onto the iPod. There are really only two steps involved in the process.
Step 1: Open the program. Either navigate through the iTunes music store to purchase your desired video, or load a video you already own (which must be encoded in the appropriate format before this step). See some of the other articles in the iPod section for ways to encode your own video.
Step 2: Sync your iPod using the iTunes interface. If the video you've loaded isn't iPod-compatible, iTunes will refuse to tranfer it, and return an error message to that effect. Safely disconnect your iPod, and navigate to your videos. Your new video should appear, ready to play.
Pros: *No guesswork *Extremely simple, normally very easy *The obvious solution for moving files to the iPod
Cons: *Must pay for iTunes music store videos *Doesn't allow encoding of new videos *Interface is not flexible *Input formats very limited *Music store content is limited