With the introduction of Apple Keynote 6 and OS Maverick release there have been many updates. We have encountered a glitch using Mac and QuickTime movies encoded with a transparent backgrounds in the new version. Using previous Keynote versions to open with their transparent backgrounds works.
While awaiting for Apple to institute a fix for this issue and support for QuickTime alpha channels, you can customize QuickTime to a color scheme that will apply to your image or to the white version. We can only hope some of the lost features of the previous version get added back in a future update. We will continue to a formulate a plan or method to circumvent this problem to enable you to create professional business presentations.