As with any of my free advice, it's usually worth what you pay for it. However, I liked this. The story is a great concept and I thought the action and the score were combined in an effective way. There could be advantages in making it much shorter, for one thing, it would give you more time to iron out the technical issues you are having with Flash. Another thing you may want to do is to develop the characters more by adding details to their faces. For example, giving the puppy eyes with moving pupils would allow you to create a character that is more alive without adding greatly to the animation workload.
I look forward to the next one.