Enable Silverlight For Safari Mac
The App Store (or Safari Extensions Gallery) lets you conveniently browse extensions and install them with a single click. It's the safest place to download Safari extensions, because all extensions in the App Store are reviewed, signed, and hosted by Apple. 
In the latest version of Safari, Apple enhanced the browser with a security measure that ensures users make use of the latest version of Flash player. The browser will check for the latest version of Flash, and if your installed version is out of date, then it will disable the plug-in and prompt you to download the latest version, but this might not always be desired. This security feature has been applauded by Adobe's Brad Arkin, who stated: 'We welcome today's initiative by Apple to encourage Mac users to stay up-to-date: With the Apple Safari 5.1.7 update released today, Apple is disabling older versions of Flash Player (specifically Flash Player 10.1.102.64 and earlier) and directing users to the Flash Player Download Center, from where they can install the latest, most secure version of Flash Player.' While this development is excellent news from a security standpoint and helps Apple regain some face after recent security mishaps on its part, some people may still wish to use older versions of Flash player for compatibility reasons. Even though new versions of the software will contain fixes to vulnerabilities, sometimes bugs may appear that result in broken functionality or poor performance, and having this auto-disable feature will force the use of faulty updates. Luckily Apple's browser does not prevent the use of older versions of Flash, and merely disables them when newer versions are available.
Therefore, if you need to revert back to a prior version of Flash when using Safari 5.1.7 or higher, you can re-enable the plug-in by going to the Macintosh HD/Library/Internet Plug-Ins (Disabled)/ folder and moving the 'Flash Player.plugin' file from this folder into the Macintosh HD/Library/Internet Plug-Ins/ folder (the one that does not have 'Disabled' in its name).
Issue: If you are facing issue with playing Netflix content through Safari since upgrading to Yosemite / El Capitan and you don’t have a secondary display connected. Specifically, Netflix will start to play the content and then display an error after a few seconds. The error reads “ Whoops, something went wrong display error. There appears to be a display problem. Please ensure your monitor is HDCP compliant and is not mirror using.” Fix HDCP Compliant display error when watching Netflix Software and OS Affected: Safari 8.0 and 9.0 on OS X Yosemite and above.
Solution to HDCP Compliant display error With Netflix on Mac This issue has obviously nothing to do with the Monitor being HDCP compliant because most of the monitor these days are HDCP compliant, still you have to be sure if your’s is. My monitor is HDCP compliant (HP ZR30W) and it’s the only monitor connected to my 2014 MacPro. As per the Netflix, if you experience the error code S7363-120 or receives HDCP compliant display error while watching Netflix videos through safari on your Mac computer, it’s typically caused by an unsupported monitor or screen or you have turned on. Follow the steps on the post. HDCP is purposely disabled via AirPlay for copy-protection. Apple only supports playback on internal monitors or through HDCP compatible monitors. Follow the troubleshooting steps below to resolve the issue.