Student taking video in class

I was teaching a power class last week. A few minutes into class I notice a student has their phone propped up taking video (themself, mostly). I told them to put the phone away and they were not pleased - even left me a 1-star review!. Do we really need to post a policy of 'no filming' now? BTW, we already encourage phones to be left outside, silenced, etc. Frankly, I'm not leaving my phone in an unattended cubby in the lobby, but you can certainly silence it and leave it alone.

Edit: Fair number of comments on the review. First, I couldn't care less about the review. Mostly a reflection on the student who couldn't take no for an answer. The review was on MindBody without any verbiage so readers have no idea what the issue was in the first place.