Good job.
I'm gonna break this down..
Audio - Kinda of annoying at the beginning when he is doing his whole weird noise screeching thing, lol. The walking, you might of wanted to choose a bit of a better stepping sound for that. Spray paint sound, is good.
Animation/Graphics - Good, good, good. Not the best but good indeed. You might want to make the guy with the can of spray paint move more up and down when he is walking to give it that more of a.. "Hey I'm walking" look, not really a "I'm sliding look at me" kinda thing.
My opinion - I think the flash itself is pretty good. I like how you actually showed him spray painting it, and actually did a good job doing it. I was really hoping for more in the flash though if you know what I mean.
Like I said you might not want to use that "screeching" sound thing for your little character guy, cause honestly it annoyed me.
Hopefully he will use some of these tips.