For Christ's sake, land sails already go 2-3 times faster than the wind using the exact same principles used in these carts.

No, they don't exactly the same principles.

Land sail, and sailboats too, cannot sail faster than the wind when they are aimed directly downwind.

But somehow, this cart can. And that's what makes it difficult to understand.

Agreed, the MIM diode seems to be shrouded in mystery. (Wikipedia, you have failed us!) From reading the links at oregonstate.edu and uspto.gov, it looks like this. A metal-insulator-metal device is a capacitor. If you make the insulator very thin, electrons can tunnel through from one metal-1 to metal-2. Also backwards, from metal-2 to metal-1. The device is inherently symmetrical, passing electrons both ways, and is not a diode but a leaky capacitor. To make it work like a diode, there has to be some asymmetry involved. One way is to bias the junction with a DC voltage. Another way is to use metal electrodes with different work functions. Either way, you make it easier for an electron to tunnel in the forward direction than going backwards -- a diode. The rest of the story is that an MIM diode can be made very small so it will work at extremely high frequencies, such as visible light, which means it could be used to rectify sunlight -- a new kind of photovoltaic device to provide solar energy.

Actually, what is the population of Earth north of 55 degrees (north latitude)? Is there any way to find that statistic?

This is weird. I swear I heard him say "E-bay" toward the end.