Can I display a different thumbnail for a Movie?

The default thumbnail generated for a movie is often not very helpful. It can be blank or have a generic copyright message that does not help identify the cataloged movie. If you select the movie and press space, the movie will begin to play. Press space again when you get to the point in the movie that you would like to appear as the thumbnail. Choose Action -> Rebuild thumbnail (or CMD-B) and this image will replace the current thumbnail.