I've created a couple tutorial videos to show how to use Overviewer to turn your iPhone into a document camera.
Overviewer with Zoom
This video shows you how the Overviewer app works and how you can share it using Zoom.
Not Using Zoom?
If you're using a video conferencing app other than Zoom such as Google Meet or Microsoft Teams this video shows how to use Overviewer using Quicktime on a Mac or Reflector on Windows.