I've re-watched the Street Magic Series where David Blaine does his double-lifts. I have to say he has one of the smoothest and virtually undetectable double-lifts I've seen in front of a live audience. Which double-lift is he using?
The revolve at the base of the thumb as the cards are turned face up stud fashion, is Martin Nash's idea dubbed as Knock out DL ( so I was told .. ) The card can be snapped over or held stationary.