But it's so great I think it bears bringing up in case anyone reading this comment has missed it. This channel animates math proofs, shows you the intuition behind fields of math, and constructs subjects in such a way as to make you feel like you could have invented them yourself. You'll still need a good textbook or something to go with the videos, but they cement the understanding in your mind very well and even open the door to more formal proofs.
My favorite video is https://www.youtube.com/watch?v=NaL_Cb42WyY . You'll have to take an additional step to get a complete proof (hint: read and work through the One Sentence Proof), but this is a beautiful piece of mathematics, shown in an understandable manner.