Takže pokud někdo narazí na tento problém, tak řešení je:
1) Move all files from /Library/QuickTime/ to a temp older on desktop
2) Open AppStore and download/install update
3) Reboot
4) Copy any missing files from temp folder on desktop to /Library/QuickTime. For me this was 1 file, AppleMPEG2Codec.component.
