It's like a house cat, with a mouse. The body language of that cat was telegraphing he (she?) was looking to jump something.
To this day I've seen nothing in a lion or a tiger that I don't see every day with our incontinent little monsters. The difference is, of course, our cats don't weigh 300+ lbs. If they did, they'd be just as dangerous and unpredictable as their bigger cousins.