People ask me about the camera I use to record these tutorials. I have been using the C920 for the last two years and find this inexpensive webcam to be better than some other expensive and more cumbersome solutions. It uses H.264 compression in the camera to allow it to send 1080p video over USB2. It works with any Mac and most apps. See a quality comparison between the C920 and the MacBook's built-in FaceTime HD camera.
You can get the C920 at NewEgg, Amazon or many other online retailers.