I thought I had this problem too, I found a tip on the E-Forums that REALLY helped and now I can do it consistently.
I can't remember exactly what it was and it's hard to describe but essentially it's this:
When you drop the bottom packet, push up on the lower half of the card near the corner. i.e. the half that's closest to the palm of your hand. The closer you can get your index finger to your palm to push the packet up, the bigger clearance you're going to get. After that, you should be able to follow the instructions as are on the DVD.
If I were to do it in step format it would be this:
1) Break deck into two.
2) Let bottom packet fall as close to the base of the fingers as possible. (your hands may need to stretch out a bit until the edge gets there, but with time it'll do it automatically)
3) Push up bottom packet with index finger as close to the bottom side (palm side) as you can.
4) Bend your thumb to break another packet from the top.
5) Continue as instructed on the DVD.
I used to not be able to do this at all, and now I do it all the time without thinking. Just keep trying at it and see if anymore tips come in.
- Sean