I was very cynical going into this. I figured he might use various film tricks to get round the necessity for sourcing 10 balls and I had strong doubts that they'd be numbered 1 to 10. Probably rigged, I thought.
However, after repeated viewings, he does indeed have 10 balls. And, for sure, they are numbered 1 to 10.
It wasn't until he swirled the balls that I truly fell in love. He does it on camera and the swirling is just enough to dispel concerns of trickery and appease any latent rage. The production reaches an apotheosis as David uses David's hand to pick a number, like it's nothing. But it's never nothing. It's always a number between 1 and 10.