It probably isn't that simple. The forward facing camera is dedicated to the safety systems. The computers and software are busy dealing with that. The simple act of recording is quite different. Just like taking a video of the kids baseball game, it will beautifully record a line drive coming straight at you but not also alert you to duck.
What they, and every car should have these days is simply a USB plug in the rear view mirror to just plug something in up there like a camera so that we don't need to run lines through the headliner. I could install it myself in two minutes.
2017 Bolt EV Premier