...but he propably memorised the cube as he was going to do a blind folded solve right
Honestly, I cannot imagine that somebody is able to solve three
cubes blindfolded at once while juggling. This would be even more incredible than assuming a very fast pattern recognition.
Probably, jugglers need a fast recognition of their objects in space, anyway?
If you have never juggled before, it might seem like the cubes are moving very fast, but they are not. As a juggler, I can watch this video and recognize patterns on the cube as he juggles. I think once you build the muscle memory pattern for juggling, it is easier to focus on other details while you juggle. There are people that master the muscle memory enough to juggle blindfolded, but it is extremely hard!
He is doing all of the solve manipulation with his left hand only, and trying to recognize patterns on the cube as he passes to his right, and then back to his left. Sometimes he throws the cube in a small spin pattern trying to see all sides. He is obviously a great juggler, and a great one handed speedcuber.
It would be very difficult to pass the cube in such a way that it lands in the correct orientation for execution of an algorithm in his left hand. As one who loves juggling and solving cubes, this is awesome. It makes me want to try it! (Not that I think I could do it, this is an amazing talent)