I think you may have had iTunes update your QuickTime and probably it defaulted to the QTX/Core AV kit, instead of the older QT framework..
Oh boy, if that is the case..
Yeah, not good.
Time to go to the QuickTime 7.6.6 and install that, at this point, you're most likely going to manually sort through your codec folders, since the release of Mavericks, it's become apparent that Apple is moving their entire audio-video base to higher efficiency formats that are compatible with the iThings that run on the mobile chips.
Not being a pro apps user, my experience is limited, but at the point where the iTunes is updating and afflicting NON-Mavericks systems, all bets are off.
OBVIOUSLY Apple is forcing this A/V change on everyone, not just Mavericks users.
Though to be honest, QT 7.2 is pretty old and a fresh install of QT 7.6.6 may re-bless your codec folder. It also really cannot hurt if you get into your Preferences folders and pull out all the quicktime preference files and let the apps rebuild new ones.
QT 7.6.6. - http://support.apple.com/kb/DL923
Try that first and see what comes of it.
