Thanks, these are the things I suspected. It just doesn't make sense. It's weird, though, because the people in the video don't look like crackpots. Maybe that woman is the only customer so far, and it's somehow easy to convince her that the bike is boosting her efforts.

I'm thinking that a bike+rider is very light and can't make much kinetic energy for regen braking.

Hmm, maybe it gives a tiny boost upon pulling away from a stop and the rider convinces herself that the boost is still going? I doubt it but maybe.

And as Grumpus says, the generator is running on the flat. So it's like a dynamo hub except maybe it's taking more than 10 watts of kinetic power which is what I think those things usually suck from the rider. I ride a bike with one of those, and I run it day and night. I don't feel the drag although I know it adds up to something. But maybe their generator is greedier. OK that's a system that could work, but it doesn't sound like a lot of fun to ride. You have to pedal really hard to charge the capacitor. And then later you get a boost from the system, but how strong and for how long?

Nope, it doesn't make sense to me. But I could be wrong.