This is getting heated. Im afraid you are fucked.
My tiny brain would recommend you not try to plead ignorance because if i were the RIAA i would be even more persuant of a ignorant bastard.
Your best bet is to be apologetic to the fact that you were stealing. And maybe play the "what would be the punishment for stealing a hard copy of the movie?" angle.
If that doesnt work, you could start stocking up on "soap on a rope".
Best of luck to you and you have now scared me away from downloading for at least two days.