The Q&A is very interesting, the bike is actually legal and he works for Apple.
He explains everything in extreme nerd detail.

I put a windsurf sail on a storm door and bolted it to a bedframe with skateboard, rollerskate and rollerblade wheels.

I had the thing going over 60 kph on one windy day.

I got kicked off the railroad by the cops saying that I was trespassing.
It was probably a blessing in disguise though, because I would have been in a world of hurt if I fell on the tracks at 60 kph. 😂