Let's summarize everything.
Did you enable camera in raspi-config tool?
Is the camera preview visible with Finder backend?
Is the camera preview visible with Finder backend with resolution set to 1280x720?
Is the camera preview visible with V4L2 backend?
Does the camera work with raspivid?
Did you do any modifications of /boot/config.txt file by hand?
Did you enable camera in raspi-config tool?
Is the camera preview visible with Finder backend?
Is the camera preview visible with Finder backend with resolution set to 1280x720?
Is the camera preview visible with V4L2 backend?
Does the camera work with raspivid?
Did you do any modifications of /boot/config.txt file by hand?