I recommend just reading the attached notes and imagery rather than the document itself. They've added pictures that show what it's talking about and clarified

I recommend just reading the attached notes and imagery rather than the document itself. They've added pictures that show what it's talking about and clarified parts of the argument that were left vague. I think they do a much better job of explaining the proof than the paper does. This is a good example of a proof that was written to be as short as possible rather than as clear as possible.