Indeed it is wild tumbling. Thanks for posting that. A person could get sea-sick if they had to watch that clip overmuch.
As you suggest, it's a good idea to expand the explanatory text below the video, it has more to say.
In particular ".... (The apparent star movement rate is greatly slowed down for illustration purposes.) ...."
So the background stars don't give you an accurate idea of how rapidly Nix is orbiting around the two main bodies Pluto-Charon.
I guess if the stars weren't slowed down separately they would whiz around 360 degrees every two seconds, which would be hard to watch. The text says the orbit period of Nix is equivalent to two seconds of video time.