Used as a key in the userInfo dictionary passed to the QTMovieMessageNotification notification to indicate the message. The associated value is an NSString.
Available in Mac OS X v10.4 and later.
Declaration Syntax Version Information- Available in Monobjc Bridge: 10.6 (For Mac OS X 10.6 and later), 10.5 (For Mac OS X 10.5 and later)