To follow up on an old thread (
http://groups.google.com/group/adwords-
api/browse_thread/thread/9a12a36b273cc09a), after a few false starts
it does now look like video ad creation in the Sandbox environment is
enabled for all users. I tested it today and my request that
previously failed now goes through.
Apologies for the length of time it took to get this resolved.
Cheers,
-Jeff Posnick, AdWords API Team