It certainly doesn't belong to Dan and Dave. The first reference that I know to it is as the "Card Twirl" in Jerry Cestkowski's Encyclopedia of Playing Card Flourishes in 2002. My instinct would be that it's a public domain idea, given that it's essentially a basic pen-spinning move, the "Finger Pass", executed with a card. If I were you, though, I'd just email Jerry out of courtesy, maybe ask him if he knows of any earlier references to it and check he's got not problem with you teaching it.