May I suggest that "Effects" and "Originality" be special awards that everyone's eligible for rather than categories of their own?
Also, is your audience going to be able to sit through a whole category devoted to intentionally bad AMVs?
AMVs submitted for non-competitive screenings will be shown at various times throughout the convention. Theses AMVs do not need to be original works.
For those that aren't original, shouldn't you at least get permission from whoever <i>did</i> make them?
And finally, who's determining the winners: judges, a fan vote, or both?