Last time I checked Sprite movies are all Tweened animation, pictures (not made by the author of the movie), length verys from 2-10 minutes, and a topic which is usally the original bad guy of the game wants to destroy the world (not to mention this is the most original plot ever), and last but not least it get a good score only because the succsess of the game it's based after.
I could understand being mad at him if you speant like half a year throughing together some flash movie that you made original characters for, speant countless hours making perfect VA lines, ect, ect. To tell the truth Sprite movies aren't that hard to put together at all, all you do is tween, this is coming from a guy who does them to. The only thing hard about them is actually finishing them because it get boring cuz they are to easy to make.
I think Illwillpress is a good animator and some of his animations are funny. Before you say his work is easy to do try actually drawing backgrounds like him and draw character models and lets not forget tweening them in the same style he does.
Well, just my opinion...