This fellow reminded me of the Joni Mitchell song "Real Good for Free," as he sat entertaining passers-by on Belgrade's pedestrian street, Knez Mihailova. Actually, I imagine he's hoping someone would give him something, but like the man reflected in the glass, many did just pass him by.
He's playing a gajde (GUY-deh), a Serbian version of bagpipes. You can see this same fellow and read more on Wikipedia !