From
https://intercallcenters.webex.com/docs/T27L/ec0605l/en_US/help/ss/host/index.htm?toc.htm?516.htmChecking your system for UCF Compatibility
If you intend to play or view Universal Communications Format (UCF) media files during the event, either as a presenter or an attendee, you can verify that the following components are installed on your computer:
Flash Player, for playing a Flash movie or interactive Flash files
Windows Media Player for playing audio or video files
Checking your system is useful if you or another presenter plans to share a UCF multimedia presentation or standalone UCF media files.
To check your system for UCF compatibility:
On the navigation bar, do one of the following:
If you are a new event service user, click New User?.
If you are already an event service user, expand Set Up, then click Event Manager.
Click Verify your rich media players.
Click the links to verify that the required players are installed on your computer.
Note: The option to check your system for required rich media players is available only if your Event Center Web site includes the UCF option.
See if that clears it up or gives any insight as a first step.
Good luck,
Anthony