I saw a lenghthy interview with the inventor of this a few years back when I was actually in the trade. Wonder how he's doing with it.
On live video, he even used his OWN FINGER to stop the blade. Didn't even bleed much since I think it cauterized immediately. Bottom line, is that he still had his finger. It was much like the demonstrationg here. He put his finger on top of a board and shoved it through the saw.
You could probably get tough guys at amusement parks to PAY for the privelege of doing that to themselves.