Are you sure he isn't manually adding a matte key? There is no way to import a file (with a matte key track) and have it automatically unlocked.
Best,
Jeff G
Certified Master Trainer | Adobe, Apple, Avid
------------
You should
follow me (filmgeek) on twitter. I promise to be nice.
My book (with Richard Harrington and Robbie Carman)-
An Editor's Guide to Adobe Premiere Pro
Lynda.com - Compressor Essentials 3.5 and 4
Contact me through my Website