"No Connected Camera"?
A simple reboot should solve the problem but if you're like me, you have no time to save all your files and restart! So try this easy quicktip in Terminal!
Symptom(s): Applications such as Facetime, Photobooth, and Skype are all giving the error "No Connected Camera".
Why?: Probably because your Macintosh had decided to reserved the camera for use in a particular process and then didn't release it on termination.
Diagnosis:
Fix 1
Open up Finder, navigate to Applications > Utilities > Terminal.
In Terminal, issue this line of code and when prompted, enter your password to execute the command.
sudo killall VDCAssistant
Now retry using your camera, it should simply fix it! If not, try this way.
Fix 2
Open up Finder, navigate to Applications > Utilities > Activity Monitor
Type "VDCAssistant" into search in the top-right corner, click the process and then click the stop icon.