I'm not David, but the way he wrapped the strings around the tailpiece is typically done to get a better break angle over the saddles, so that the tailpiece can be screwed down flush with the body and the strings will clear the back of the bridge without touching. It is kind of an old school way of doing it that you don't see a lot of, but is the way I string mine as well. Some people think that you get more sustain with the tailpiece flush to the body(I tend to agree).