As is the case with any computer software, Apple’s QuickTime video software is pretty much constantly updating itself. Sometimes this can cause issues with movies not playing correctly. Recently this has come to light when teachers are trying to play the ARMT math videos in the district’s Moodle course.
If you are having issues with the videos playing you might want to try updating QuickTime. You can get the download at http://www.apple.com/quicktime/download/ . Make sure to download the one without Itunes to make the download faster. After you download and run the file everything should work for you. If you are still having issues please feel free to contact me at firstname.lastname@example.org.