TV Can't stop the signal:
As Rob says, you couldn't see this Asylum prequel unless "you had a US subscription to iTunes or Amazon InstantVideo" or as is the case now someone handy with a computer and a YouTube account. It's unfortunate that the BBC are creating treats like this now that aren't available to the wider populace but I suppose you could argue they have the same status as the spin-off media ("He's back and it's about £13.99!") except with Matt doing some proper acting opposite a headless monk (which is why I wasn't sure about embedding it) (um) (updated later: Steven now says its available on UK iTunes in quite a bald tweet) (perhaps words have been had).
Plus it would have only been intriguing before the episode went out. It doesn't tell us anything more than is in the first thirty seconds of the teaser. But seeing the Doctor in repose is always fun and goes to underscore that for much of his incarnation the Eleventh Doctor is a lone sonicscrewdriverman, which continues his rationalisation from The God Complex that his companions really are just a variable he has to worry about along with all the other mayhem and chaos which fills his life on a nanosecondy basis. Asylum is a prime example. If he hadn't had to keep Amy alive, find Rory and get their marriage back on track, the discovery of Oswin's secret would have been much swifter.