Having the same problem with 32bit machines. Flash works unless it's embedded on a page. I can see the still frame of the video, but when I click to play it goes white and will flicker in and out when I move the cursor around.
We've tried uninstalling and reinstalling evreything: IE9, Flash. Running debuggers, activeX settings, add-ins and everything we could find. Even went so far as to re-image the machine after running some registry cleaners that seemed to fix the problem, but then jacked up everything else.
Only current work around is to roll back to IE8.
I've run out of ideas, so I'm posting here in hopes someone, somewhere has found the solution.