Well, after spending eight hours working demanding jobs, be it physical or mentally, everyday people usually like to spend their free time with something a little more relaxing, and for most people that isn't reading documentation or reading highky technical engineering papers but rather watching a highly enthusiastic guy try and share his joy of rocket science.

Content can be also be entertaining to watch. Not everyone wants to superoptimize their time.

Then just read a university text-book and don't look for that in a educational video.