It was the sliding dice method of throwing them. I couldn't do it, but it is a technique that will allow one of the two dice to have the number the thrower keeps on top before throwing. In other words, if I kept the number 6 on top and threw the two dice I would be assured that the numbers that came out at the other end would be 7 through 12. The one dice with the 6 number on top would slide across the craps table and the second dice would bounce normally. So when they stop in their motion, the total will be 7 (6 plus 1), 8 (6 plus 2), 9 (6 plus 3), et cetera, on up to 12 (6 plus 6).
This may be helpful to someone who is betting with odds on what numbers will come out. In other words, Snake Eyes through 6 will not be coming out when the dice thrower throws the dice with the sliding method, if they are successful.
I can't imagine it's a perfect science each throw, but maybe I'm wrong.