Beijing Olympics Monkey Animation 2008..

I've always loved this. Everything about it is amazing. The character designs, concept, animation, music and background art.

I would really like to learn the method they used for making it. I'm guessing the background has been done in 3d with painted textures. The animation looks 2D yet they move quite nicely in a 3d space so maybe they're actually done in 3d but made to look more

cartoony then a typical Maya character.. Maybe the characters are a mixture of 2d and 3d...if anyone has a better idea of the production process behind this please let me know !