what does it mean when it shows block plug-in

1. System Preferences > Flash > Advanced > Delete All

2. Install Adobe Flash Player.

http://get.adobe.com/flashplayer/

Quit Safari.

Restart computer. Relaunch Safari.

I would highly recommend “ClickToFlash”, this extension blocks all flash. Click the flash content you want to see, i.e video on youtube. Why, you might ask. Your computer will run a lot smoother.

If you still get a ‘plug-ins blocked’ message:

http://support.apple.com/kb/HT5271