very good animation... most of the time we feel that the cart is heavy! I like the jump/fall too.
the only time I don't feel the weight of the cart is at the beginning when he pulls it the 2 first time, it seems a bit easy, maybe it should be a bit slower. Also it's a bit strange that the handle of the cart is fixed... I would see it rotate.
last thing is as the cart is heavy, it should go down faster around frame 190.
I really enjoy it! I love exercice with weight, it really shows the power of animation.

Mathas.