I'm a skeptic. I watched part of one of the videos where he's explaining it, and right before the crucial acceleration, he completely obscures the device from view. This seems pretty conservation-of-energy-non-complient to me.

I can't believe this is legitimate without a walkthrough of all the electronics behind it. Anyone can make a youtube video, and anyone can make claims. He may have had a friend turn on a supplementary motor or something.

We just don't know.