I am highly skeptical. The amount of energy you can extract from the wind is a function of swept area for a conventional wind turbine. I don't see how this is

I am highly skeptical. The amount of energy you can extract from the wind is a function of swept area for a conventional wind turbine. I don't see how this is going to be much different, even if it is incredibly efficient. "swept area" in the video is, what, around 6 square meters? So about the same as a wind turbine of 1.9m in diameter. If it has the same efficiency, we're talking about maybe 1600W maximum. The design may, or may not be good and dependable, and may, or may not require less maintenance than a conventional wind turbine. But a lot of the problem is mounting it on a roof. There's a reason why the commercial units are being built bigger and bigger, and higher and higher. The higher up you go, the more steady and strong the wind becomes. At rooftop level, a lot of the wind is blocked by trees and buildings. So I don't care how good the turbine design is, mounting it on a roof isn't a great solution for generating much power.