I won't comment on the costume, but I would recommend against putting "screentests" online.

The language is completely immature and makes the whole thing sound so juvenile. "Butt-buddies"? You really think Batman would say something like that?

Why would this kid that looks like he's 12 years old and sneaking around on his parents know where the Joker is? The Batman voice wasn't too bad, but all of the acting is pretty rough. Especially the little boy. Using much quicker edits in the action scenes will make them seem a little more dynamic.