The guy's channel revolves around solutions that are super-cheap so that someone handy in a poor country can easily source the materials to build the thing. So I imagine some of his design decisions are based on his knowledge of what materials are locally available to relatively poor people in various places in Africa, or Panema, or Tibet, or wherever.

I was watching another one of his videos, and he was trying to get a bike chain to act as a belt for his wind turbine, and his rationale was that bike chains are easily accessible in poor countries, but he had to fall back on a car drive belt that was cut down and modified because he couldn't get his first option to work.