Finding such a movie clip sounds extremely unpleasant and I would need more of an incentive to start trying. (Playing the AI in an AI box experiment also sounds extremely unpleasant for the same reason.)
I know it sounds like I'm avoiding having to justify my assertion here, and... that's because I totally am. I suspect on general principles that most successful strategies for getting out of the box involve saying horrible, horrible things, and I don't want to get much more specific than those general principles because I don't want to get too close to horrible, horrible things.
Like when you say "horrible, horrible things". What do you mean?
Driving a wedge between the gatekeeper and his or her loved ones? Threats? Exploiting any guilt or self-loathing the gatekeeper feels? Appealing to the gatekeeper's sense of obligation by twisting his or her interpretation of authority figures, objects of admiration, and internalized sense of honor? Asserting cynicism and general apathy towards the fate of mankind?
For all but the last one it seems like you'd need an in-depth knowledge of the gatekeeper's psyche and personal life.
Update 2013-09-05.
I have since played two more AI box experiments after this one, winning both.
Update 2013-12-30:
I have lost two more AI box experiments, and won two more. Current Record is 3 Wins, 3 Losses.