If you're running into difficulties displaying Flash video, one of the first troubleshooting steps is to disable hardware acceleration in Flash Player.
It's a simple process but I've seen situations where getting access to the "Settings" dialog has been disabled. Because of that, I'd recommend the following:
1. Navigate to the Find Flash Player Version page.
2. Verify that you are in the section titled "Find Flash Player version type and capabilities (Flash developers only)"
3. Right click on your Player version and select "Settings"
4. The Settings dialog will appear, change the tab at the bottom to display (if not already there) and uncheck (or if you'd like to enable, check) the "Enable hardware acceleration" checkbox.
5. Close the dialog and restart your browser.