It could have had some sort of assist on it. None of the tractors, implements, or cars I have seen used anything but a crank going into the end of the crankshaft.
I understand that broken bones were not uncommon back in the Model T days.
After I bought the Lincoln SA200 (1952 model) and it kicked me several times, I asked the PO about it and he said the same type engine knocked most of his brothers front teeth out while cranking a combine.
I bought the parts to convert it to electric start soon after but it still had crank capability.
For whatever reason, they did not put the exhaust manifold on it when they started it. At the end of the video, they show an old picture of it with the manifold on it.
Anything is going to sound evil without at least having zoomie tubes.
The Model T was famous for kicking back if you set the spark just a little off Broken arms were so common the were called “A Ford Fracture”