When a Flash video refuses to play on a Mac, it feels a little contrary to the old advertising slogan, "It just works." Legitimate reasons why a Mac won't play Flash videos range from disabled features to software errors. When troubleshooting, confirm Flash is installed and activated before presuming something's gone wrong with Flash or the video itself.
Flash Isn't Installed
Macs do not support Flash video content natively and can't play back Flash files unless Flash is installed. Apple removed Adobe Flash from new Mac models in late 2010. While Flash is no longer installed out of the box, you can install it yourself through Adobe's website. Flash videos play correctly in Web browsers if Flash is installed and activated on the system.
Flash Is Disabled
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The Video's Bad
Sometimes the Mac does "just work," and the problem has nothing to do with your end. If Flash is installed and enabled, the video you're trying to watch could be the problem. Flash video may incorporate security procedures to halt play back of content that isn't properly set up, or the video file could be corrupted. Try watching the content on another computer or Flash-compatible device. If it still doesn't work, then the video is likely the problem. However, don't reach for an iPad to test it: The iOS platform doesn't support Flash at the time of publication.
Update Drivers and Flash
Some Flash video issues can be resolved by updating Flash to the most recent version and by updating the Mac's drivers. To update Flash, go to the Adobe Flash Player download site and select Mac from the download options. Download and run the installer. Update the Mac's drivers by clicking on the Apple icon in the menu and selecting "Software Update." Install any available updates listed in the menu.
Uninstall and Clean Install
If the Flash installation has a problem, it's faster to start over than to troubleshoot. Download and run the Adobe Flash Uninstaller program for Macs to remove the program. After removing Flash, go to the Adobe Flash Player site. Download and run the latest version Mac installer.