Is there an overview of the file formats QTKit understands?
You are using the QTMovie + movieFileTypes: method picking a type parameter from:
QTIncludeStillImageTypes QTIncludeTranslatableTypes QTIncludeAggressiveTypes QTIncludeCommonTypes QTIncludeAllTypes
Besides the programmatic QTMovie + movieFileTypes, Bob says, you can also check the Quicktime Player Spec page:
http://www.apple.com/quicktime/player/specs.html