You would think that making a generator out of a bigger version of that would work just fine. Environmentally friendly too.
Notice the bearing he used? He used it dry. If any stress was on it, it would need grease and grease would slow it down. I doubt those balls would even turn a greased bearing. It would need a very high tech, totally frictionless bearing.
The vanes are like fan blades. They're pushing air which will eventually slow it down.
Count the balls on the inside vs the outside. At any given time, the number of balls moving down on the ouside is almost the same as those moving up so the gravitational pull is equal. But then, the down moving balls on the outside are also having to lift the up moving inside balls as there is nothing to balance them. In the photo, there are 3 down moving balls, 1 of which is almost at the bottom and isn't contributing to the motion. On the left are 2 up moving balls and 1 that is neutral at the bottom. So, the up and down motion is almost neutral. But, there are 5 inside balls being lifted. You'd have to do some measuring and some math, but you'd find that their total weight would be at least that of 1 outside ball.