Alright right then here's now they do it.
A lot of the later stuff such as the rabbit, balloon, and flash light are already setup. They've had bees sitting in them since the act began. But the earlier things such as the tube (which you never get to see empty but I'm sure is) and pot are obviously empty. However you never get to see the other side of the cloth and lid, which I'm certain have groups of bees bearding under them. So they're actually placing small gatherings of workers (probably attracted by queen pheromone,) into the pot and tube and suddenly fall after the lid or cloth is jerked away.
I haven't quite figured out the first thing they do yet with bees coming out of his hand. But I'm sure it could be done with practice. Perhaps he's holding the bees between his fingers.