What does the black rectangle clipper when filming films and movies actually do? Why do they need one at all?

Question

I always wondered this

In: 133

Answer 1

Even in smaller productions, it’s helpful to record the take and scene. I was editing together a video recorded on my phone, and it was super annoying to figure out which one was the take where I coughed halfway through, or forgot a word… I had written down “#1,#2, etc but when I uploaded and started rearranging clips it was useless. If I had used a sign within the clip to designate it as “scene 1, take 1” it would have been easier