If you tap the top of the screen, the front camera will be used
if you select the bottom of the screen you'll start recording by the rear camera.

You can use Wide or Ultra Wide camera for rear camera recording, just open settings and change the currently used camera.

Set your own background, use a predefined black one, or record with a full-screen preview.
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PLEASE NOTE:
It's against iOS Developer Program Licence Agreement to not have indicators on the screen when taking a video.