We have been struggling with this problem , we know that people just loves to copy everything thay can and nothing is 100% safe. Our digigobos series are copied a lot, also custom content that are left on a hire machine. I always try to clean the discs after a production....but......

QuickTime has built-in support for encryption using media keys--only viewers who have the key can view the media. It's very similar to the way you unlock QuickTime Pro's editing features. Currently, only Sorenson video has implemented media key protection as an option for their codecs.

One option should be that you ( as in Maxedia / Hippotizer ) are loading in your stuff into a file that can´t be moved from the unit, just deleted...