I hope you are not being snarky, because to anyone else the following may be somewhat obvious: "Stop!" is for benefit of others listening, + more attention-gr

I hope you are not being snarky, because to anyone else the following may be somewhat obvious: "Stop!" is for benefit of others listening, + more attention-grabbing than "Help!" because it could be targeted at anyone in the vicinity or it could be an abbreviated call for action + conveys more information than "Help!" or "Fire!" because it contains the action requested. No idea about "So, ____________" [not an American]. Perhaps in this case it was seeking clear confirmation for the camera, though.