No one learns to operate this kind of machinery, to the level that this youngster is, on an occasional basis. Noting that his operation of the machine is interesting enough to video I’d guess that he might be the son of one of the owner of the plant.
We have no way to know for sure. But given China’s one-child law, and Chinese school attendance requirements of nine hour days, Monday through Friday, he’s probably been doing this for a while after school. Sadly, he doesn’t look too excited to be running this thing (as you might expect a child to be (I would have been)) which might lead us to believe that it’s de rigueur for him.