Rhinos have a temperament similar to dogs. As long as you don't intentionally fuck with them they're typically chill. They're likely friends and playing otherwise I doubt the zookeepers would have let this happen.

I was thinking at 13 seconds in, the little dance-hop it makes then wags it's tail.. the body movement.. That rhino kinda was giving off "let's play!" vibes.

Rhinos are just armored puppy dogs. Hippos are the sketchy ones. Even though rhinos look hardcore and hippos look cute.