This all is a really good discussion.
Apple apparently wants to be serious about professional video products. All their video products use QT as a backbone. They SHOULD start a ProApp version of QT (which will simple be, say QT 7.3) that is highly compatible with video applications.
IF you have FCP Studio on your system, software update sees this and only provides options for ProApp version of QT (say 7.5).
7.4 has created SO MUCH havoc. More than a lot of previous updates it seems. All in the name of iTunes. Great – there’s the piggy bank, but “all users of QT 7” we are not