UPDATED: Set Video Kind of Selected v3.1
Set Video Kind of Selected had a small problem running in Tiger: it couldn't get the version of iTunes correctly and threw an error. This is fixed in this latest version.
This script will change the video kind property of the selected tracks to your choice of "Movie", "Music Video" or "TV Show". Additionally, "Show Name", "Season Number", and "Episode Number" can also be set or cleared for each selected track.