Apple has updated QuickTime to version 6.1.1. The new version delivers what Apple calls important bug fixes to MPEG-4 streaming. We know this because of the one-line note that comes with the download in Software Update:
QuickTime 6.1.1 delivers important bug fixes to MPEG-4 streaming.
As of this writing, QuickTime 6.1.1 is available only through the Software Update Control Panel. The download is 19.4 MB.
Apple usually adds an article to the Knowledge Base at some point after an update is released through Software Update, and it should also eventually be available directly through Appleis download site . You can find more information on QuickTime at Appleis QuickTime Web page.