Quesion RE: TBBT "The Zazzy Substitution"

Just saw this ep. On Demand, and got to wondering, like I always do when I see it, how does an animal trainer get all those cats to sit still? Are those just unusual cats, or were they all given a dose of Valium before shooting the episode?

I have an unusual cat who likes meeting new people, and unlike a normal cat, would not run away and hide if you put her in front of a camera, but she’d be going nuts trying to get everyone’s attention. She’d be tapping Jim Parsons with her paw until he pet her, then she’d run over to Johnny Galecki as soon as he walked into the room and try to jump on him.

Usually when I see a cat on TV, there’s something obvious, like it’s licking a spot on the furniture, where they obviously smeared butter or something, to get the cat to stay on its mark. But these cats were just hanging out.

How’d they do this?