I've been doing the deck flip non stop for the past week and I've got it every time.
To any of the readers/posters out there who are having a hard time with this one... I promise, just keep at it and you will get it. I tried it a few times here and there for a while, but never felt consistent with it. One day I just decided to figure the damn thing out. Here is a list of things to evolve over time to improve the effects consistency & flow:
1.) Find you own subtle positions for your fingers on the cards! For me, the thumb played a HUGE role in this. I have a set position for it that it actually different from the way a lot of people do it that I've seen in videos.
2.) Make sure to "pop" rather than "scrape." These words should trigger something in your head if you are having problems with the cards flying out.
3.) Just sit there any practice it for a while on a Sunday or something so you can just relax and figure out all the little details.
4.) Believe in yourself and you can do anything. That's what my mom tells me. I haven't gotten that job as an astronaut yet though, maybe next year.
(Btw, I am hoping this isn't exposure. I still recommend that people buy The Trilogy to learn this, because that tutorial was extremely helpful.)