Each domino is 1.5 times taller, thicker, and wider than the previous. But it is still able to topple the next.
This demo appears to be a violation of conservation of energy. You start it with a small amount of energy and a large amount of energy comes out. It is important to remember that the energy was put into the system when you setup the dominos. Just like the small match that can set a forest ablaze, the tiny double-zero domino is in a position to start a sequence of events that cause the giant double-twelve to fall with a thud!