If you are not sure whether Adobe Flash Player is installed in your web browser and if installed, what version of the Flash Player are your running - here's a simple trick.
Visit this page on Adobe.com. If you have the Adobe Flash Player plugin, the page will display the exact version of the Flash Player. If Flash is missing on your machine, you won't see the line the says "Adobe Flash Player is Installed."
Make sure you perform this check separately for IE and Firefox / Opera.
What's new in Flash Player 9 that's on Adobe Labs
While the latest version of Adobe Flash Player is 188.8.131.52, Adobe have recently released an updated version of Macromedia Flash Player 9 (184.108.40.206) that supports H.264 in addition to the original On2 VP6 codec (but not Sorenson Video).
Why upgrade to Flash Player 9 with H.264 support
What that means in simple jargon is that you can now use the same Flash Player 9 to play Quicktime .mov and the iPod .mp4, m4v videos in your web browser without installing the Apple Quicktime plugin. Video encoded in Quicktime or MPEG-4 formats (not divx or xvid) will play in the Flash Player just like other Flash Video files (e.g. YouTube) and SWF movies.
Before you download Flash Player 9 H.264 version, make sure you clean up you existing installation of Flash Player 9 / 8 else the upgrade will fail.