As you may know you can encrypt movies and use our OpenMovieWithCustomQTDataHandlerMBS function to load them for playback. Now in recent plugins 13.0/13.1 there was a little change. The key for decryption is now a memoryblock instead of a string. And you have to keep this memoryblock alive as it's used by the plugin. So please change code using OpenMovieWithCustomQTDataHandlerMBS to now pass a memoryblock and keep this memoryblock in a property of your window. The memoryblock must be alive until you close the movie.
Our plugin allows you to use XOR (Faster) or AES (slower) encryption which allows you to deliver movies with your application, but the user can't simply double click them and play them outside your application.