Hi Matt,
Although Apple's Quicktime is officially working in 64-bit mode in Windows 7, I believe there are certain components of QT that are not fully 64-bit compatible which has caused some issue.
I'm not 100% up to date with this situation, but believe this to still be the case... All I can suggest for PC users currently that wish to run Windows in 64-bit mode is to use one the workarounds (to emulate 32-bit mode) and/or use NEDweb to view their purchased tutorials online.
Please contact our Support team for the latest info:
http://www.macprovideo.com/support/
Thanks
Rounik