What would you do if you were in a public place and a complete stranger started videotaping you?

I was about 29 and I had taken the kids to Cowtown. I was sitting on a bench, just resting, watching the kids when I realized….this guy a few feet away from me, to my right, was video taping me! Wow. So, when I realized it I paused for a moment, then turned and faced him head on…and gave him my most brilliant smile! LOL! I didn’t know what else to do! I didn’t feel threatened. It was just very odd!
No, he wasn’t video taping the kids. Just me.