I'm pretty sure it's real. I've seen cats that when you touch a certain spot, they'll react in a certain way every time. It's not something that can be trained, though.
A friend of mine's cat, when you pet him on his rear will wash his right front leg. I have a kitten that when you touch the base of his tail with a toy, he'll trill. Come to think of it, I have a female kitten that every time you pass a laser pointer over her head (on the ceiling), she cackles like The Preditor. And these cats will do the same action EVERY time, over and over.
My guess is they were touching her foot, or scratching just the right spot to make her react that way. I'm not completely conviced that her voice wasn't altered to make it more high pitched, but it's possible that it's her real voice.