He had to use Yahtzee's style of speaking, didn't he?
Yahtzee himself said that he didn't even realize he was talking fast until Russ pointed it out to him. I imagine he doesn't really strain to get the words out as fast as possible, he just goes for it and it comes out quickly and clearly.
I guess this illustrates the point that Yahtzee's style of speaking isn't for everyone. The guy should have practiced this a few dozen times so he could nail it, because it's bloody hard to decipher what he's saying.