Apple released the latest update to Lion last week, version 10.7.4, which also updated Safari to 5.1.7. One of the features of this new Safari is to block older versions of Adobe Flash Player. This is causing some problems; the typical support call is “it could get to a web page yesterday, then I got a Software Update, now it doesn’t work anymore.”
By itself, Safari can’t read certain web page content without the help of plugins. Out of the box, Safari supports QuickTime and viewing PDF files online. If you want to watch videos from YouTube, you need the Flash Player plugin from Adobe. Most of the time when Flash is needed, you will get a note on the web page; click on that note and you’re taken to Adobe’s web page to download the Flash Player.
The reason for this is because Apple considers older versions of Flash Player to be vulnerable to various malware attacks, so they have added code to Safari to block these versions from running to better protect you. If Safari sees an outdated version, it will act as if no Flash Player is installed at all, so you will get a prompt to install it the next time it’s needed.
Another example of a plugin is Silverlight, which is required to watch Netflix on your Mac. Java is also an plugin, but is not included with Lion due to recent security issues. Most of the time when you try to view a page that requires a plugin you don’t have, a link is provided to install it.
Note that plugins are not the same as extensions. I have seen some review sites use the terms synonymously, but in fact they are not the same thing. Plugins are required to view web page content, while extensions add to the functionality of Safari itself. 1Password has a browser extension to fill in logins and passwords for you; another example is AdBlock, which prevents advertisements from showing on web pages.
When prompted for a plugin, first ensure that you’re familiar with the site. If you are viewing a Yahoo news page and a plugin request comes up, it’s most likely safe to install it. If you’re searching for something on Google, and a random page pops up a “missing plugin” error, there is always the chance that it’s not safe to install. Better to back out of that page and look elsewhere than to risk infection by malware. You can always search on Google for that plugin—if it’s harmful, there will be reports of it.
Once the plugin is downloaded, click the “Show downloads” arrow on the Safari toolbar, then double-click the Adobe Flash installer. It will open up a disk image containing a red Flash icon. Double click on this icon and follow the prompts to install it. Once it’s complete, go back to the web page and it should now work properly.