Lostify is an MP4 metadata tagger which supports some iTunes-specific tags. It is based on the open-source command line utility AtomicParsley, but wraps it in an easy-to-use graphical interface.
The primary purpose of Lostify is to allow users to tag their MP4 and M4V videos in the same ways as the ones purchased through the iTunes music store. Most of these "private" metadata fields are exposed, which cannot be set through the iTunes interface. Using Lostify, you can tag your TV Shows as "TV Show", and set the show, series and episode information, so that iTunes, iPod, iPhone, Front Row and Apple TV will display your own tagged videos alongside those purchased through iTunes.