I want to add something else about the rearing.
If you look good, you see he goes up by throwing his head up in the air, and then his feet follow.
This is VERY bad for his back! Even for a fullgrown horse it's bad, but for this young guy.. You could get your horse injured, seriously, no joke.
You should really really really work on that if you're gonna keep doing this. One thing you could try is to let him walk forward (instead of backward like you did in the video) and than ask him to rear, so he will step forward with his hindlegs and put them under the mass.
But if you want my real advice; don't do rearing anymore until he is older so his joints are better and his muscles are more developed.
Sorry! Bad english.. feel free to correct me (: