Cops use that one, because they know it's legally sound. A few months ago, I saw a video by a homeowner -- he walked out of his house and stood close to some cops who were hassling someone. The cops didn't notice for awhile. Then they did. All of a sudden it was: "Turn off the camera, and go back inside." The homeowner refused. The cop says, "Sir, I'm worried about what you might do, based on what you said just before you turned that camera on ..."
It was clear that nothing was said by the homeowner. But the cop had the lingo down. Basically, "I was afraid for my life" which is why I would be justified in beating you soundly with my nightstick.
“you sure I’m the only one filming this little interaction, officer? How do you know my wife isn’t inside filming this, too?”