draw testing.
Watch and listen to that part carefully.

I like the part where they talk about what they do when a digit comes up 3 times in the same position. If it comes up 2 of 3 again, they pull the ballset, like there is something wrong with it.
Then you can hear one of them chuckle and say, It's all random, it's just the luck of the draw. So then why pull it?