This is unbelievable, but is a Guinness World record, so it must be kosher, no? What a talent to not only juggle, but manipulate the cubes in your hand for the brief time you have them so that their faces eventually align. I wonder if you can make a living out of this.
Here are the YouTube notes:
The fastest time to solve three Rubik’s cubes whilst juggling is 5 mins 2.43 sec, achieved by Que Jianyu (China), on the set of ‘La Notte dei Record’, in Rome, Italy, on 17 November 2018.