QuickTime can sometimes take over as the handler for Flash content, either from the installation or by actively selecting it as the default handler.
Starting in QuickTime 7.3.1 this should no longer be an issue because the Flash media handler in QuickTime has been disabled for security reasons. Make sure that you upgrade your installation of QuickTime.
If you cannot upgrade QuickTime to the latest version, you may be able to reconfigure an older version of QuickTime so that it does not handle Flash content. See Use the QuickTime plugin to play audio and video for more information.
- Open the QuickTime Player.
- At the top of the QuickTime window, select the menu, select , and then select . The QuickTime Preferences window appears.
- In the QuickTime Preferences window, select the Browser tab, and then click . The MIME Types window opens.
- Expand the Miscellaneous category and, if found, remove the check mark from "Flash Media".
- Click , then restart your computer.
- From the Apple menu, click . The System Preferences window appears.
- In the System Preferences window, click , select the Advanced tab, and then click . The MIME Types window opens.
- Expand the Miscellaneous category and, if found, remove the check mark from "Flash Media".
Flash content on websites can now be handled by the Adobe Flash Player.
Based on information from Flash (mozillaZine KB)