Nifty, though I'm a bit confused as to what they're actually controling with the equipment...

Ah! That is understandable since you are only see part of it the whole package. Since mice are so small in my universe it is impossible for them to play traditional musical instruments. What Melody and Harmony developed originally in college was a series of sensors and transmitters that would pickup the speed and location of a performers limbs while dancing within a specfic designated stage area and covert those movements into specific acoustical tones or notes. Also the floor of the stage is set up so stepping certain areas produce specfic notes. Literally how they danced or moved produced their music. Hence the name of the group Move to the Music. It has gone through several revisions with each getting more sophisticated.

Think of it like Dance Dance Revolution in reverse:
Your movements are what make the music, rather than the music making your movements.

<grins> Great art! Great concept! Its nice to see that Movement Controlled Music isn't just a crazy idea I had. If others have thought it, its gotta be ligit.
My version involves a blind and mute honey badger pianist who collaborates with a music school's AV whiz and his crazy new 'instrument' which he calls a Vulpetron. Pic is here: http://www.furaffinity.net/view/403008/

but it would be so much more cute to have them playing tiny guitars :P