I am just trying to drill down deeper as to what the issue is with running Quicktime 7.7.7. with Cubase Pro 8.02 in Windows 10 (other than that Quicktime is getting rather long in the tooth).
I’m sure I read Ed Doll saying something about Quicktime installation issues in WIn 10 - I’ve had no issues at all and so far Win 10 is working well for me,
He did here Windows 10 - please do not upgrade! - Cubase - Steinberg Forums
Ed also said not all systems are affected - maybe I am one of the lucky ones - either that or there is a monster lurking! 
At the moment I can’t see any other issue except that in 7.7.7 Apple has changed the installer to detect Windows 10 and refuse to install. People who already have it installed when upgrading or use a workaround I posted earlier How to install Quicktime 7.7.7 on Windows 10 - Steinberg Lounge - Steinberg Forums to install will have it working fine.