Why the H-Perm algorithm works [DE]

In most tutorials on the Rubik's Cube, you are simply presented with algorithms without an explanation of why they work. In this series, I will look at the algorithms for the Rubik's Cube and explain how they work. So it's about really understanding these algorithms.
In this video, we'll look at how you actually come up with the H-Perm algorithm, which is used to permute the edges in the last layer.