Actually...some things don't make sense. I suspect the video maybe was staged. There seemed to be nothing coming out of the zoomie stacks, and even at idle during warm-up, the injector butterflies were full open. If there had been any bay doors, they would have been open, and there was no evidence of that. I know diesels are different than gasoline engines. Typically, on a dyno, the exhaust is ducted outside through a muffler system and flex hose. Yes, the Gilmer belts were moving, but still.
These Detroit Diesels are "2-cycle", with exhaust ports cut in the cylinder walls exactly like a McCoy .60. But there is also a cam that operates a valve in the cylinder head, along with a glowplug and probably an injector. I really haven't got my mind around that yet. I helped take one of these (a straight 6, I think) out of a fishing boat...maybe 60' or so. We took it apart and hauled the pieces out. They are high rpm engines and are not fuel misers. Then, we put in a bigger diesel... probably a Caterpillar, but maybe a Cummins. Bear in mind that this was about 40 years ago, on a Monday.

Steve