The lead instrument in this video is a friction instrument called Spools & Wheels. By rotating any of the wheels at the front of the instrument, the player creates a stick-slip vibration in a looped string. The vibration transmits to a diaphragm covering the end of an air-resonance tube, and it’s the natural frequency of the tube that provides the pitch that you hear.
For more instruments by Bart Hopkin, visit the Instrumentarium at www.BartHopkin.com.
And by the way! Bart has recently released an album of his music, made primarily on instruments he's made. It's called Audiorium, and it's available through the usual download and streaming services.
