I know you guys are always right “there” when it comes to stuff like this, but it’s my first time seeing it and maybe it will be your first time as well.
To save those of you who HAVE seen it some time, it’s a video of a very young Oriental kid playing drums to a Joan Jett tune sent to me by a friend.
The expressions on his face just gives me acute cute attacks! 
http://www.angelfire.com/ak2/intelligencerreport/drummer.html
Quasi
Okay, let’s be controversial:
How do you train a 4 year old to do that when most of them can’t even muster enough co-ordination to color within the lines?
As far as I can tell, the human ability to learn peaks at birth and its a steady decline from that point on. Think of how readily four year olds can learn two languages, something that vastly more difficult for a thirty year old to accomplish.
You might like this series of youtube videos of a young boy playing various drum songs. I believe the earliest is from when the kid is 3.