Windows 8 is a great OS, better than 7 in every way, but since the start menu changed, its obviously trash. Humanity is just dumb.
Two things come to mind:
He is correct that its usability suffers from Metro and the abrupt changes to the UI when it is being pushed so hard. One of many points made in the video was that people who have never used it will find it very confusing because in more ways than one the UI gets in the way. Microsoft trying to have its cake and eat it too is what is causing all this grief. Instead of doing like Apple did with the change from OS9 to OS10 and dropping legacy and backwards compatibility to go with the new paradigm they want to maintain backwards compatibility. This is because Microsoft fears backlash from both its main customers, big businesses and governments, and the developers for those businesses and governments. Worse, they really made it for the tablet market all the while still trying to hold onto the laptop / desktop market with it. The point made in the video of the differences between a mouse / touchpad and touchscreen are valid.
To do it right, Metro should NOT be the default interface if you are installing it to a machine without a touchscreen just as the "classic" should not be the default if you are installing it to a tablet. They are different beasts. A tablet is more for viewing content than it is a great workhorse for making that content no matter what Microsoft or Apple may think. An even better solution is to do two different products. One for the tablets and one for the desktop / laptop and let the consumers choose which they really want for what products. Again, that too was pointed out in this video.
The second observation of your post deals with your contempt for humans. It is those very humans that Microsoft is trying to impress. There is a very, very large segment of the population that are not pleased with the Metro interface that Microsoft really wants to go with. The so called "fix" of downloading a second application to eliminate it as the advice that is often given is proof enough of that dislike. Calling that many people names isn't the way to win over support.