It is no secret that you can build all kinds of fun LEGO models. The Bat happens to be a motorized kinetic LEGO sculpture that flaps its wings, expands, and contracts them. It is modeled after a fruit bat and simply reproduces the wing motion of the creature.
The base is responsible for moving the whole body. The wings are made with LEGO flex tube for the most part. JK Brickworks has more info here.