The real start is on the next pages which goes into _real_ deep intro for Diodes and transistors. I think it was just a matter of giving an intro but overseeing that people don't know what these symbols mean.
For me, an electronics engineer by degree (not by trade), it was so basic I could see the author forgetting this.
I wonder how popular this tag must be/have been to be able to find someone that had already dissolved/sandpapered it? Can't wait for the follow-up on this, turn that e-waste into something usable!
Videos are really the thing where you just can't get around large formats. There's only so much you can compress, and even then if there is a lot of movement or color change even compressing won't do much.