All of the people doing the "10 foot challenge" are looking down at the ground. Looking down at the ground in front of your bicycle (or motorcycle, or any two wheel vehicle) results in a ton of shaking and instability in the handlebars. They're making the challenge about 100x harder for themselves.

I would have taken this guy's $200 by simply lining the bike up, keeping my eyes on the horizon, and giving the pedal one solid enough push. I would probably give it back too since I violated the spirit of the challenge. :-)

Interesting video. It's funny how countersteering is a seemingly innate ability, but if you explain it to people they will deny that is how a bicycle works.