I saw this post that mentioned that Pixar has a video podcast that goes over different areas of the production of Cars. I though that this would be interesting to see, so I added it to iTunes. Today, I noticed that the video files were not appearing on my iPod. It appears that when Pixar created the videos, that they are not using MPEG 4, but another QuickTime format.
I would think that a company, as closely related to Apple as Pixar is, would want these things to be available on iPods, without conversion.