I almost took a star off for him hitting all of the strings open over and over, a sound which has driven me crazy since I started playing guitar, but this is just too cool not to give 5 to.
That was fun, a kind of capture I hadn't seen before and in real time. The thick low strings looked the most sine, and you could see the actual non sine waves, like triangles in the higher strings. That would probably be close to what a wave editor would show too.
I hadn't thought that harmonics showed up in the strings of a guitar at all, it was all sine, but that the coloration came from the box resonating.