I have a Macbook Pro and two camera: the internal isight camera and a USB Logitech camera.
I can configure both in icam source, but cannot start either, the "Start" button is greyed-out.
I have tried using each with photobooth when both are active, that works. I can switch from one to the other.
I have tried unplugging the Logitech, but still cannot start the internal camera.
I have re-started iCam source a number of times and have rebooted the computer with the Logitech camera plugged-in.
No luck.