The JavaScript function Media devices.getUserMedia() will do this, and also includes screen sharing possibilities. It will ask the user for permission first but in a test situation, there's high pressure to accept those permissions or fail the test.
Sounds great. Maybe some harmless pre-recorded loop. Whatever it takes to defeat their surveillance. Also I bet someday someone will come up with some AI thing to generate that video feed...
https://testrtc.com/manipulating-getusermedia-available-devi...