The 4.2 Camera is legit
FOR THE GALAXY NEXUS ONLY
1. Download the 4.2Camera.zip
2. Place the zip file on the root of your phone’s storage.
3. Reboot into your recovery.
4. Just in case, make a backup.
5. Flash the 4.2Camera.zip file. (No need to wipe anything)
6. Once installed, reboot your phone.
7. Lastly, enjoy it!