[TheAdamAndChe]

+1 for AvE[1]. He's NSFW compared to bible school due to cussing and occasionally dirty jokes, but he uses language that pretty much any manual laborer in the country encounters daily. His analysis of how things are designed have taught me all sorts of things about how tools are made.

[1]https://www.youtube.com/user/arduinoversusevil

[walrus01]

I would also recommend this guy's youtube channel, he disassembles and examines both normally priced and suspiciously-cheap-from-china consumer electronics:

https://www.youtube.com/user/bigclivedotcom/videos