You'd be amazed what engineers can do using computer technology to control stuff. Getting something to stay upright in an unstable position is a class project at my university. It probably works on the same principles as the segue. And, they're not planning on this going very fast: 20 mph top speed. Crashing on it would be no worse than crashing on a bicycle (which can still get ugly). I think its legit, or could be if you had someone with the know how and the passion for it.