Zhenya, Ana and I heard the strange music while standing on the triple bridge. At first I thought it was a saw player but as we got closer it was clear that the man was playing a homemade Theremin. His set-up included a PA system, mini disk player, CD player, all hacked into a homemade case and powered by a small gas generator 20 feet away and behind a sound baffle. Wonderful!

UPDATE:

Just a few hours after posting the video on YouTube someone called copperleaves made this very informative comment:

The busker is Romanian thereminist, Benedict Popescu. Other videos of this very unusual musician playing his even more unusual theremin can be found here on YouTube.