This should work for both Classic and OS X. Just play the movie with each version of QuickTime Player. In Classic, these will appear as extensions in the System Folder -> Extensions -> QuickTime Extensions folder.
This seems to be the only change in QT 5.0.4. These are the same components included on the new FinalCut Pro 3.0 installer CD.
[Editor's note: It appears this movie has been pulled from the referenced webpage. I'm leaving the article here as some of the discussion below contains useful information.]

