From the video's description:
David Garland plays a 1980's classic on a 12 string guitar modified by his son, Kenji. This guitar uses an electroacoustic feedback loop (pickup in, transducer out ---i think the transducer is under the bridge?)
wow, amazing! truly my fav. oldschool dgarland jam, now singing in a totally different light thanks to Kenji's amazing work. 3garlands 4eva
[ thx Daniel ]