That video is the perfect response for why this is a silly idea. A clever chat bot can beat the Turing test, but in a TED talk you don't even have to deal with probing questions. All you have to do is babble on about something vaguely inspiring.
Yeah, I was already wondering how they were going to reconcile that particular speech with whatever nuances of the prize rules would be required to keep people from giving a speech like that one.
It gets weirder when you consider that a) an AI could have plausibly (though not likely) have generated such a speech in answer to a real question (for example, "discuss a flaw in the TED program", and b) no one rejected Watts' talk as unacceptable, though they probably would have if an AI had generated the same talk.