newrow_ automatically selects the default media input devices from within Video Chatting in an open meeting.
If your camera does not activate, make sure your camera is selected in the drop down menu.
If not, navigate the drop down listing camera drivers and select the one that should be activated.
Make sure your camera is operational if it still does not activate. If it is an external camera make sure you are properly connected, powered, and that the appropriate drivers have been installed for your computer to recognize the camera.