Wow...that's just amazing.
Just think of being one of those people. You will have to memorize your steps pretty much the whole way, as you won't be in a position where you can actually see what the end result will look like. You can't afford to slip up or even be late, as it would make the whole result fall apart.
And as a manager...how do you even start to create such a thing? Setting up a static image is hard enough (getting everyone in a good spot from a distance, so you keep your overview)...but moving from one image to the next? Creating a MOVING image? (like that horse).
Christ...the more I think of it, the more in awe I am. It's just...amazing!