I cannot imagine hand cranking an engine that size. I have almost had joints pulled out of their sockets cranking a VF4D Wisconsin on a Lincoln SA200 welder.
The bruises that crank would leave were impressive.
Love the Barracuda in the background.
Back around 1960 my best friend had to plow his parents field with a Farmall Cub. It looked like a large tractor only a bit smaller.
One day he got it stuck in a hole and it would not pull itself out. He got out the hand crank which you had to use to start it, and literally cranked it out of the hole by hand.
I thought it looked like it had some king of spring wound hand crank setup, unless it just has such a long stroke it pushes over TDC with such high compression, then with a little late ignition spark it take off. The crank was a major stroker just looking at it in the video.
It actually made me jump...I been a diesel mech for a long time and that big four cylinder sounded damn scary.
I would not spend a lot of time next to it.