Phone prompter test
Open this in Chrome on your iPhone. It checks whether your phone can film you and follow your voice at the same time.
What your phone can do
The 10-second test
Tap start, allow the camera and microphone, then read this out loud: "Everyone is selling a course on editing your reels with Claude. I set mine up this week."
10
Result
Play it back. Check you can hear yourself and the picture isn't flipped.