i think its probably a guitar synth i heard that the roland gs-20 and gs-30 have really great orchestral sounds, and have no tracking probloms if they are set up right. but if it is a roland guitar synth it would have to have an internal synth pick up, because i didn't see any wires coming out from under the bridge pick up, or the controls the wire would go to that are usally duct taped or velcroed to the side of the guitar. i couldnt tell if the guitar had a synth pic up on it, because if tis a roland it would be black and mounted between the bridge pick up and the bridge.
it could also be a sound to midi converter (i think thats wha thtey're called), but i heard that the tracking on those are horrible. Oh, just incase you couldn't tell, ima bit of a synth geek