You gotta grow!
I can't really share anything that hasn't been expressed already.
I can sort of make out boundaries you've set up for yourself in the flash; even in the nice hand-drawn graphics and the blood (very good job on the blood) I could see the background items (like corpses or blood splatters) that were tweened against the background movement, so you might want to add some extra layers just to play it safe. What I'd also recommend is reviewing any positions the humans excecuted that you saw as less-than-satisfactory, and start drawing them to familiarize yourself with smoother actions.
Just remember, the bar has lifted significantly since flashes even a year ago: people expect decent voice acting in something like this, but if you expound on your drawings and add some more originality to the story you'll definately get away with some more fives.
I'll look forward to seeing your next flash in my inbox, but until then, don't stop growing!