I can't get it working. I've tried in vanilla (no content/script blocking) Firefox and Chrome. I've accepted the microphone permission, but it seems there's a hard requirement on having a camera attached? I'm getting:

"DOMException: The object can not be found here." - FF

and

"DOMException: Requested device not found" - Chrome

Since you state you can turn both the camera and microphone off, I think it'd be much better UX to not force camera and mic access up front.

Also, Firefox asked for permission before I clicked on the "Request Permissions" button.

Screenshots: https://imgur.com/a/BKY5bcE