Yeah, funny video.
It isn't real and is fake, you can tell by the fact that the punches aren't hard, when the young guy fell he did so on purpose, the old guy didn't even try to take him down, he just fell over, they are just playing around, more shown by the fact that the young guy is doing a monkey dance and someone is filming it from start to finish by coincidence. Still funny, though.
In real life, old men just seem to run back to their car and drive off at the slightest hint of danger. That's been my experience anyways, which is good, they are fragile and anyone who actually hits an old man should go to jail, it's like hitting a child when they get up there in age.