I do not click on these videos as it only encourages more such shit videos, but they are funny nonetheless. In the past I have watched their heavy machinery repair ones. The repairs were just shit and they had zero knowledge of what they were doing.
I saw one repair where a dozer drive sprocket pushes onto a tapered spline on a big steel hub. It is a critical dimension as it also locates a seal. The splines can flog loose over a long time period especially if not maintained correctly. So in this video they got their stick welder out and weld it up. No heat treatment. Then they get an angle grinder and "grind" in new precision splines. The repair would not have even worked.
This is what the splines look like on a good one, could you imagine cutting them with an angle grinder? It is what happens when a society does not develop the understanding of why something is done. But rather handed the technology. Like that video on youtube of the person going on about a "death ray" 400V capacitor. Did not know what happens when you rectify 240VAC.