Why are my movies grayed out?

There are two causes that result in movies showing as grayed out on the on-screen display:  
 
All movies that are downloaded using the factory download service will be grayed out until they receive playback authorization. To initiate the authorization process, send an email to factory-download-service@kaleidescape.com containing the serial number of the device and the email address used to register the store account. Playback authorization will occur within 1 business day.  
 
Playback authorization is removed from a system when it is removed from its original account and re-registered to an account linked to a different email address.