I think he is pushing on that piece of rebar with both feet to keep tension on the belt. I was going to say that I hope he has medical insurance, but they're in a civilized country where everybody has medical coverage.
Yea it's dangerous but it's ingenious at the same time. I mean that there is a swamp cooler pulley on that crank!
I would make it a bit safer by having permanent foot holds off the frame and have like a hand lever cable drawn with a spring like a clutch off your handlebars. Lever out spring takes over belt is engaged clutch in belt is disengaged.
That set up if you have to make a panic stop your body would automatically want to push that re-barb engaging that engine some more then your hand brakes won't work that great and you are heading for the river oh noes.