Isn't there some famous/well know banjo song that uses the quick detuning similar to this? I saw Livingston Taylor do it but I can't remember anything more about it.

If you go back further into this guy's youtube channel you will hear some great stuff. There is one called saomething like "The hardest solo ever" that was a great piece of funk. Thumbing, slapping, tapping, hammer-ons and pull offs... all of it.

If you don't know about Victor Wooten, check him out too. Wooten is from another planet completely.