If the whole hose acts as a tube, then a) the sound is coming of the edges, which are far away from the microphone, and b) he gets pretty damn precise pitches and with very good articulation, which I imagine will be tricky on a garden hose since it's made of hard rubber, and thus is depressible if you press it, which you have to, in order to close the holes adequately enough to produce the sounds. Also, the holes are very close to each another, while the tube is quite long, which makes little sense. It may be true and I may be overlooking many many things, but all I see is a video. I'd love to see it live so the person could explain me how it works
