From the Samsung support page:
•After I installed the update, I can no longer access the Avatar movie as I receive "File Locked" message. What can I do?
•The license will need to be reacquired. You may need to backup information as a reset will erase all device data. A full reset will need to be performed by dialing *2767*3855#. The device will restart afterwards. After a few minutes has passed, you should be able to play back the movie.
That sucks ass. So you have to fully reset your phone to get avatar playable again.