Camera not working again on mid 2013 Macbook Air after the second 10.8.5 upgrade
So, if I understand correctly, you did these steps:


Upgraded to 10.8.5
Found the camera didn't work in Skype
Backed up /Library/CoreMediaIO/Plug-Ins/DAL/AppleCamera.plugin
Put AppleCamera.plugin from 10.8.4 in its place
Camera worked
Upgraded to 10.8.5 Supplemental Update
Camera broken again


The Supplemental Update does include a copy of AppleCamera.plugin (see below), so one quick thing to try:


Put your copy of AppleCamera.plugin from step (3) back into place
Download the 10.8.5 Supplemental Update again.  You can get it as a DMG file from Apple DL1686
Re-run that update (double click the .pkg file in the DMG)


By the way, you can see what files are contained within the update: double click the .pkg file, then choose File > Show Files from the installer.