Hey Stephen, good to hear from you!
That video is great, I've seen people use wax finishes, but never with that sort of tool. I remember Hank Gilpin using a wax finish on the piece he did for the 1989 New American Furniture show at the Museum of Fine Arts in Boston. I think he said he applied it with a stiff bristle brush. Pretty sure Krenov also used wax finishes, he introduced us to Renaissance Micro-Crystaline wax when he taught at RIT.
Doesn't seem like a good choice for banjos, but maybe for some furniture I've been wanting to build for home, if I ever find the time. The big question here is whether it would attract our dog to chew on it, vs linseed oil. Anyone have any thoughts?