plug in failure
video plug-in failures
iMac, Mac OS X (10.6.8)
After installing Flash Player, reboot your Mac and relaunch Safari, then in Safari Preferences/Security enable ‘Allow Plugins’. If you are running 10.6.8 or later:
When you have installed the latest version of Flash, relaunch Safari and test.
If you're getting a "blocked plug-in" error, then in System Preferences… ▹ Flash Player ▹ Advanced
click Check Now. Quit and relaunch your browser.