Dammit, this is going to lead to a whole new set of questions from confused family members.
"How do I get to Start > Programs > [Some app which was made for usage on Windows XP]? I can't find the Start button, this new Windows is no good. grumble"
There's nothing particularly amazing about watching a man try to navigate a system he hasn't been taught how to navigate. Most of these kinds of experiments tend to end the same way, unless the system includes metaphors the users are already well accustomed to using.
I don't think there's any question Microsoft will include an extensive tutorial in Windows 8's final release. If they don't, we can safely laugh at them. As it is, though, this video is rubbish. I could make a similar video filming my Grandmother trying to use Windows 7(She only knows how to use a specific type of Web TV, sans mouse). I guarantee you we'll see similar results.
Windows has a massive install base. One of Microsoft's most important tasks will be to train their current users to make the transition to this new UI. It's not a small feat. But this video completely sidesteps the most important part in the process, and instead asks a man to use a novel, manufactured system with nothing but his natural inclinations. On those grounds, I think he does quite well. But the video is rubbish.
There's another video at http://www.youtube.com/watch?v=XeeOkHjV7nM where he is asked to use a mac for the first time in his life. The guy has apparently used XP for many years and is a die-hard windows fan. Watch how quickly he is able to pick it up (with zero instruction) in comparison to Win8.
The Win8 start screen isn't hard to get to - if you know how. I'll have no trouble with it, you'll have no trouble with it, and anyone who is given a tutorial or basic training will have no trouble with it.
But I'll bet there's going to be millions of users who find themselves in the same situation as the guy in the video, and it's going to be a nightmare for any company who tries to deploy this to all their users.
For me the big take-away is this:
Important user interface elements should be visible on screen.
I'm troubled by the invisible UI stuff, including the hot corners. And I'm worried because knowledge of these features is required to operate the system at a basic level. That's kind of frightening. Not insurmountable, but frightening.
I think OSX's interface elements are more approachable than these hidden elements, given his(and most people's) prior experience. If you've used Windows, you're not going to be a stranger to drop down menus or desktop like icons (a la the dock).
And I agree that the invisible user interface elements will be a nightmare for IT people around the world. But to be frank, I don't want to restrict change to things that make IT folks happy ;) (Of course, I'm not a company worth a few hundred billion dollars whose livelihood depends on enterprise acceptance...)
I'm interested in seeing how long it will take for these 'new' UI concepts, where screen edges and corners are elements to be touched and modified, to sink into the general consciousness. It seems to have sunk into the OSX world rather quickly. Now it's time to see how the other 90% cope with it.
"How do I get to Start > Programs > [Some app which was made for usage on Windows XP]? I can't find the Start button, this new Windows is no good. grumble"