Definite Potential
The idea was good. I think you could have done a bit more with it, though. Though this movie didn't have a lot of things happening in it, it still seemed very long. There were several spots toward the beginning that seemed needlessly drawn out, like the ball panting and looking back and forth repeatedly. Also, as someone earlier mentioned, it would be a good idea to clean up your art a little. It's way better than what a big percentage of Newgrounds can dish out, but it seemed to lack semblance.
Overall, it was okay - there are a lot of things that you could work on, though. What saddens with this is that there were a lot of things that you could have done with the central theme of this video, but didn't. You're obviously quite good, but elaborating on your theme, cleaning up the artwork just a little, and shortening the time between events (i.e. the ball escaping and the kid finding it again.) One more thing that I think would be nice, though you obviously don't have to do it, is adding depth to the characters. Anyway, all that aside, you have a lot of potential as a Flash artist, and I look forward to seeing more of your stuff!
...It would sure suck to be a kickball, though...