How can I record the screen and the rear camera on an iPhone simultaneously? I've seen many apps that can record the iPhone screen and the front camera (facecam) into a single video. It embeds the facecam into a corner of the iPhone screen recording.

I want an app to record the rear camera and combine the video/overlay the video with the screen recording.

Basically I want to make a video showing how a WiFi light bulb reacts when using the iPhone app (screen controls).
So as I record the screen of the iPhone showing the changing the settings of the bulb on the app, I want to use the rear camera to simultaneously record and embed into the screen recording what's happening with the bulb in real time.

The key here is the rear camera, there are software which use the front camera (facecam) and screen recording at the same time but I can't find any app (or a way) to use the rear camera and the screen recording at the same time.

Is this something apps can do on the iPhone with iOS?
In the absence of an app that allows overlaying screen recording and a rear camera recording simultaneously (odd why the app makers didn't provide an option to select the rear camera instead of just the front facing camera), here is a workaround I found.


Record the screen recording using the iOS screen recorder
Record the rear camera video using the iOS camera app
Download iMovie from the App Store and overlay the two recordings together (split, picture in picture etc).


Here is a video tutorial I found on YouTube which explains how to combine/overlay two recordings/videos using iMovie on iOS.

https://www.youtube.com/watch?v=D_qx75zTjr0

I'm not marking this as the answer as this is not my ideal scenario, it would have been nice to have an app do it, but it's a workaround for now.