Good job! You seem to have a good handle on the poses. (Plus seeing Sintel backflip off the tree was pretty sweet.)
There was a little bit lacking in there, I’m afraid.
First, in the movement, Sintel seems almost weightless for the entire thing. Try to work on adding more animation principles in there, such as squash and stretch, follow through, and timing and spacing, to help with the weightless issue. (we need to see that Sintel is being pulled down by gravity when she lands on the ground, for instance.)
Secondly, this definitely could use some more polishing. One could argue that the almost stepped movement can be a problem or a style, I could care less about either, it looks decent. I’m more worried about the facial expressions, or lack thereof. Get me some more facial expressions.
Overall, you seem to have a good handle on posing and animation but you should definitely study the article and try to apply my advice to the animation. Good job!