I wish my reflexes were that good. 
Those kids could have been badly cut by the mirror.
He dives towards the ground to catch the mirror. Reminds me of a football player going for a low pass.
Pretty amazing though he came close to squashing the kid himself.
That mirror should have been hung on the wall. It looks like it was just leaning against it. A accident waiting to happen.
There’s a subreddit for that!
Of course there is! 
I’ve seen compliation videos of this kind of thing floating round on the net for a few years. Reflexes like a frickin bat. Respect!