Historical Videos/Channels
Dark Skies
Dark Skies is an educational aerospace history channel that talks about secret or forgotten planes, aviation projects, and more! It is a great way to learn about the many genius planes in the past that looked great on paper but were too expensive or unreliable in the skies above. Overall, it truly brings you to the realm of experimental aviation and gives you an insight into the origins of genius aeronautical design today.
How Does a P-51 Mustang Work?
This is a great, in-depth video that uses 3D animation to explain all of the various structures and operations of the P-51 Mustang.
Jared Owen
Jared Owen is a great 3D designer who uses his skill to explain how things work. He does a great job at explaining stuff like the ISS and apollo program. He is the whole reason I got interested in aerospace and even considered joining CAP!
Greg's Automobiles and Airplanes
This is, frankly, an awesome channel. One who dives deeply into the technical elements of WWII aviation. A multi-hour-long series diving into the P-47's construction and armament, 30 minutes on the Wildcat's supercharging system, and a discussion of the engineering of the FW-190 or ME-163. All of this, you shall find, and much, you shall learn. Check it out!
Spacecraft & Rocket Commentator Channels
Scott Manley has made many YouTube videos explaining recent events regarding rockets and has many Kerbal Space Program videos that will help give you an insight into what space travel is like and what it involves.
Everyday Astronaut is one of the most famous space commentators. Has data and information-rich videos for those who love specific details about certain launches, engines, rockets, etc.
Clear, chronological, fantastically engaging outlines of major battles during WWII - With maps to show the precise positions of units in 'real time', which I have no idea how he reconstructs. It's cool, nevertheless.
He also has a second one, The Intel Report, which is equally cool.