The most common propulsion system is a large drive shaft that is attached to the engine crank shaft directly driving the propeller system. Next is the diesel or LNG electric: The engine turns a huge generator that produces electricity to turn a electric motor that the propeller is attached to underneath the ship. This arrangement is know as Azipor electric propulsion system. Finally, there is a water jet propulsion system. A huge water pump forces water through a nozzle below the water line to both steer and propel the ship.

Propulsion units and engines are not the same thing. Replacing external propulsion units whilst not in dry dock and running is NOT possible.

Next, pistons are installed…”(shows connecting rod) “pistons are connected to the crankshaft” (no, no they’re not. They’re connected to the connecting rods)

The largest combustion engines ever built can be found in container ships. However, the engines in the new ultra large container ships tend to be smaller in size and power but instead on one main engine, they have two main engines and two propellers.

All the main engines in large container ships and tankers are two-stroke engines. In ones has to be pedantic about the clip, it is not mere the turbochargers ability to compress the combustion air for the engine that increases the efficiency of the engine. It is also the fact that the turbocharger is driven by the exhaust gas.

The part in the video where pistons are mentioned, the shown is not a piston but a crosshead. Since this type engine is very tall (long piston stroke), a device is needed between the piston rod and the crankshaft to covert the rotating motion of the crankshaft to a vertical movement of the piston. This is the job of the crosshead. On top of the crosshead, the piston rod is mounted. In principle all two stroke main engine may be considered low speed engines since they typically operates at a max rpm of 85 - 160 rpm depending on the size of the engine.