Morning jbacoustic,
Thanks for using Apple Support Communities.
If you have issues playing media from a third-party device, make sure the software that accompanied the device is installed on your computer.
For more information on this, take a look at this article:
Adding additional media format support to QuickTime
http://support.apple.com/kb/HT3526
Also try renaming the file to end in .m4v only.
Best of luck,
Mario