Apple's operating system does not allow our app to capture your screen and camera at the same time. Instead of creating a video that includes a screen recording and facecam recording at the same time, you can overlay a facecam recording onto an existing screen recording.
Overlay a facecam video
To overlay a facecam, tap an existing screen recording in the app to open it. Next, tap the Facecam icon in the tool bar at the bottom of the screen.
A facecam tile is inserted on the screen. You can drag it to reposition it anywhere over the existing recording. Tap Rec to playback the recording and make your facecam recording.

Note: Turn the Keep original audio toggle switch keep to the on position to keep the original video's audio. Turn this control to the off position to use the facecam audio (for example, if narration during the facecam video is the audio you want to keep).
When you are finished recording, tap the pause button.
If you are happy with your facecam recording, you can tap Merge to merge the facecam recording and source video into a single file.
Tap Save a copy to save the merged recording as a new file, or tap Modify to modify the original recording.