I've watched that clip several times. My nieces got a big charge out of it, so I would put on the NK videos when I needed a break from girl drama. We found the choreography - the synced head-bobbing, the turning and acknowledging each other while playing, and so forth - to be as interesting as the actual playing. It bothered me - not enough to quit watching, but did bother me nonetheless - that had any one of these kiddos made the slightest mistake in a performance, their entire families probably, at the very least by way of consequences, would have gone hungry for a week.
If they are doing because it is fun for them, and they show talent, GO for it! But if they aren't really interested, and are being forced into it, that can cause a lifetime of being out-of-sync with other people and should be stopped
I saw kids with fingers now healed from countless hours, days, months of practice, not being forced to work in fields or on top of trash dumps, but neither being permitted to be toddlers.
They are cute and disciplined, but the price was too high. Indoctrination is indoctrination.