Some web pages still use the legacy Quicktime 7 plug-in for media. Newer versions of OS X do not enable this plug-in. Your browser may say that the plug-in is missing or not supported even when Quicktimes is installed and up-to-date.
In order to view the media the plug-in will need to be restored.
Choose Go and click Go to Folder from the menu bar in the finder.
Type Library/Internet Plug-ins in the search bar and click Go.
While holding down COMMAND (⌘), double click the Disabled Plug-ins folder to open it in a new window.
Drag the QuickTime Plugin.plugin and nslQTScriptablePlugin.xpt files into the Internet Plug-ins folder.
If asked to authenticate click authenticate and enter the administrator login and password.
Close out of the browser and reopen. It should now display the media.