I've managed to find the answer to this myself. (Is there no-one from Adobe here?)
Quicktime has a feature, mostly hidden from users, which is designed to adjust the display gamma of quicktime movies on different machines to compensate for display difference. Deep within the file, there is sometimes a little tag called 'gama' lurking which tells the Quicktime player what gamma correction the file was encoded with. While this is well-intentioned, motivated by the difference in display gamma between PCs and Macs, the Quicktime player offers no way to view this tag and change it.
To work around this issue, Frantic Films Software "created a small tool that strips the 'gama' tag out of offending quicktimes. It's a very simple tool which operates on all the file names and folders given to it."
This QuicktimeGammaStripper utility (for Windows) disappeared in the last few months, but it popped up here http://rapidshare.com/files/124507779/QuicktimeGammaStripper.zip
AFAIK the way QT displays your movie is NOT an accurate respresentation of the movie itself, but an attempt to adjust to the type of system you have. Stripping out the gamma setting 'fixes' this. If the QT movie is uploaded to, say YouTube, this gamma is stripped out as a matter of course.
(Is there no-one from Adobe here?)
Generally, no. It's pretty much just users. To get help on issues like this from Adobe, you'd need a paid support plan.
the way QT displays your movie is NOT an accurate respresentation of the movie
All the more reason not to use Quicktime.
Being a Mac standard is enough of a reason. I don't even have any version of Quicktime installed any any of three machines.
Thank you for reporting on your "fix." I've seen quite a few posts in several fora about the end results, but your's is the first mention of a Gamma-correction tag within the file itself. Though I have not come up against it, I'll be sure to link to your post for others.
As to the question about an Adobe presence, there is usually not one, or at least not one that we users are aware of. I'd hope that there are some product people, who do read these fora, but would *guess* that it would only be the forum for the "current" version. Adobe provides the henhouse, but we're all just users here.