[wanderingmoose]

I really like the welch labs series on imaginary numbers which covers the first part of what you talk about -- leveling up the notion of what a complex number is. Though his focus was more on solving simple equations with no real roots, but really detailing how/what is really going on.

It is a great precursor to then thinking about quaternions

https://www.youtube.com/watch?v=T647CGsuOVU&list=PLiaHhY2iBX...

[quantadev]

That exact video is the one that always comes to my mind when thinking of YT videos on this! I've seen it years ago. Definitely worth a watch for anyone who hasn't see it!