I'm going to use this opportunity to list some relatively unknown yet excellent software dev related channels that I've come across over the years.

* Derek Banas (https://www.youtube.com/user/derekbanas): staggering amount of content on a huge variety of programming topics; tutorial-style; this guy is so productive it scares me sometimes :(

* Mark Lewis (https://www.youtube.com/user/DrMarkCLewis): CS professor; lots of videos on general CS, functional programming; focus on Scala

* VoidRealms (https://www.youtube.com/channel/UCYP0nk48grsMwO3iL8YaAKA): excellent C++-focused content, great Qt series

* mathematicalmonk (https://www.youtube.com/user/mathematicalmonk): great ML and probability videos

* mycodeschool (https://www.youtube.com/user/mycodeschool): general CS, algorithms, data structures

* HandmadeHero (https://www.youtube.com/user/handmadeheroarchive): excellent series by Casey Muratori that explains a huge number of topics related to game dev, gfx programming; has a really long series of videos documenting how he's building an indie game from the ground up i.e. custom engine

I will update once I think of others :)