I am a great fan of Martin A. Nash's work and rigth now I am putting together a gambling routine for my private performances.

In his video series "The very best of Martin A. Nash" I stumbled across a flourish, which he calls "Throw Cut" and "Snap Cut":
He hold the deck in straddle grip with his left hand and suddenly the lower part of the deck jumps into his right hand.

This move can be seen on his first DVD from this set at 13m:52s and 45m:16s and on his 5th DVD at 12m:38s and 40m:17s (right after the tabled faro flourish).

Does anyone know how this move is called in the literature and where I can learn it from?

I guess there must be some sort of tension in the deck, but I can not figure out what. To me it does not seem as if he only uses his first finger to throw the lower packet towards him.

Any hint or help is highly appreciated!