Usually I would not point out a typo, but this one makes it difficult to grasp the magnitude of potential improvements:

> the number of nodes A* has to explore decreases from 12693 to 12693

It's a little unclear, but it's a live updating number, if you follow the directions, you'll see the second number decrease.

Good catch. I was thinking people would read that after they have moved the green L but I should handle both before and after moving L.