3Blue1Brown is one of the best math educators on YouTube. As a matter of fact, I would say he's the best I know of at the moment. I'm currently working my way through his series on diff-eq.
https://www.youtube.com/watch?v=rB83DpBJQsE&feature=youtu.be...
Here's a little bit of quote from the video:
=====
So... typically this is the part where there might be some kind of sponsor message. But one thing I want to do with the channel moving ahead is to stop doing sponsored content, and instead make things just about the direct relationship with the audience.
I mean that not only in the sense of the funding model, with direct support through Patreon, but also in the sense that I think these videos can better accomplish their goal if each one feels like it's just about you and me sharing in a love of math, with no other motive, especially in the cases where viewers are students.
=====
He's really a good person. I'm glad that now he is able to do this full-time by just the support from his patreon.
NB: MathTheBeautiful [1] is by MIT alum Pavel Grinfeld [2]. He approaches Linear Algebra from a geometric perspective as well, but with more emphasis on the mechanics of solving equations. He has a ton of videos organized into several courses, ranging from in-depth Intro to Linear Algebra courses to more advanced courses on PDEs and Tensor Calculus. Highly recommended.
Esp note his video on Legendre polynomials [3] and Why {1,x,x²} Is a Terrible Basis: https://www.youtube.com/watch?v=pYoGYQOXqTk&index=14&list=PL....
[1] MathTheBeautiful https://www.youtube.com/channel/UCr22xikWUK2yUW4YxOKXclQ
I just realized there's a deep connection among your recommendations...Gilbert Strang was Greenfield's PhD advisor: https://dspace.mit.edu/handle/1721.1/29345. Pavel has a clear and precise teaching style like Strang, and I've heard him reference Prof's Strang's courses before but didn't make the connection. Good trees produce good fruit. The small world graph and the truth of that never ceases to amaze. Good trees, good stuff.
I would pair with Gilbert Strang MIT open courseware and Khan Academy. The 3 together made linear algebra probably the most useful mathematics class Ive taken.