Our own Matt Richardson is up to some fantastic things at the Interactive Telecommunications Program at NYU- check out his group project, digidrench:

digidrench is an interactive video installation in which the user controls video playback by filling and draining three tanks. As the water level rises, the video plays forward; as it lowers, the video reverses. The user gets to interact with the very same materials that are used on screen. As the user pours, liquid falls on screen. There is a direct correlation between the user’s action and the video content, allowing for more playful and meaningful engagement with the project.

Inside the tanks, fluid level sensors relay water levels to an Arduino, which in turn passes those values along to a computer running Max with Jitter. Max uses the data from the Arduino to “scrub” the video playheads back and forth.