Wow! I did not know this existed. It's a 2-minute animation made by Yuri Norstein as his segment of a 2003 Japanese animated movie called Winter Days. It's simply beautiful. I can't stop watching it. Those leaves and trees in the wind are stunning. The two characters are so real and so expressive. Norstein is the guy who made Hedgehog in the Fog which is posted below. This is what it's all about. Want to animate? Stare at this for several days and you will probably know how to do it.
Go watch the Norstein segment from Winter Days