Where can you place a portal on a moving surface in Portal 2?

I've heard there are places in Portal 2 where it is possible to place a portal on a moving surface without the portal disappearing? What chamber is this in, and is it possible that I played through it, or is it a required mechanism of the game?


Chapter 5 - Area 3

When you have to cut the tubes of the neurotoxin generator.

But I think it's the only place in the game. Correct me if I'm wrong!