it is indeed very impressive and the craftsmanship is unbelievable, but I don;t think the engine is running on its own, at least not on fuel I don't think. There is no source of ignition so it can't be gas powered. I don't think it is diesel because I don't think that engine can create the amount of compression required to ignite diesel besides there is no glow plug so how the hell did he fire it when it was cold. The other thing is that there is not a trace of exhaust fumes.
I believe that the engine is running on compressed air.