YouTube Master List
YouTube is a great place to find great content, unfortunately you have to dig to find it. "Surface" YouTube is a terrible cocktail of reaction videos, clickbait, and low effort content.
Luckily I've been able to find a decent number of great channels, so here is my list:
CGP Grey
Probably one of the best YouTube creators around, he makes videos over a broad range of topics.
Baz Battles
Does a great video game like representation of historic battles with tons of background and history mixed in.
engineerguy
Bill Hamock does a great job explaining engineering and technology principals and designs.
kaptainkristian
Pop culture "love letters"
Kurzgesagt
Much like CGP Grey (they do twin videos sometimes), covers a lot of different topics
Lessons from the Screenplay
Discussions about cinema
Lindybeige
Covers topics from dance to military history, but mainly focuses on history
Military History Visualized
Great creator who covers many topics of warfare
NativLang
Videos about language, how they work, and their history
Now You See It
Another channel about cinema
Primitive Technology
A man who never speaks builds the most incredible things out of mud and muscle
Real Engineering
Covers a ton of topics about various engineering topics and issues
The Great War
This is more of a series than a collection of videos, it covers World War I, week by week
The School of Life
Some of their more recent stuff is meh, but their Philosophy, History, and Politics videos are great
Tom Scott
Great videos about things you might not know
Wendover Productions
Videos about engineering topics that changed the world