If you have already installed QuickTime Player on your computer, and think you have the Plug In, check the folder for your browser application. Inside this folder will be a folder called "Plugins". If you do not see a QuickTime Plugin in this folder, but you do have QuickTime on your computer, you will need to go to the Quicktime application folder, make a copy of the Plugin that is there and put it in the browser application plugins folder.