I imagine what happens after this one is he just makes it a bigger black rectangle.
This will allow for map tiles that are taller than the 64 pixels show up properly.
This wouldn't be a problem if the entire map and player were redrawn on every step. Since the map is only drawn once (at the beginning of the stage load), editing the depth of the player is the key.
Anyway, all this does is allow for more dynamic looking maps, which will be useful in the upcoming virtual museum game.
When you approach and run into an exhibit item, like the mushroom on the plinth, the game will pop up a more detailed rendering and description of the item. It's like going through an annotated photo slideshow, but takes longer because you physically have to walk to each thing.
When I describe it that way it sounds awful. Lololol.