This video is of a tank of water with computer generated fish projected in the tank. When you touch the water, the fish react. In the video, I think I moved too fast or confused the fish, because they don't seem to be running from me poking the water. There weren't any directions...so maybe I wasn't supposed to poke the water.
This video is from another water exhibit in the same area. A fountain of water creates a water "shell". The shell shrinks as you put your hand closer and then expands when nobody is touching it.
Here is the official SIGGRAPH info.