Notably, they are not colliding with each other, I don't think. That is what he meant by adding pressure. If you made it more like a "flood fill" of the maze,

Notably, they are not colliding with each other, I don't think. That is what he meant by adding pressure. If you made it more like a "flood fill" of the maze, where new particles are pushing into the maze, that would be similar. Though, I would guess that the earlier particles added would be higher probability to get out first. (Which would fit the intuition.)