There's an easier way to get QT7 into a Snow Leopard Mac - I just figured this out the other day myself. If you try and open a .qtz file on Snow Leopard, the OS jumps onto the Internet and downloads QT7 - presumably these file ares unsupported in SL. I didn't have a .qtz file on my Macbook, so I copied any old file on my Desktop and renamed it: filename.qtz. When I double clicked, the OS did all the work and installed QT7 onto the Mac.
I paid for QT7 Pro some time ago, and I was missing all the nice export features, so this trick got me up and running again.