Mozilla / Firefox Security Settings
Mozilla / Firefox will default to using Windows Media Player if another program is not specified.
Mozilla settings

Open Firefox >>

Pull down the Tools Menu >>

Select Options >>

Click on the Content Tab >>

Under File Types, click on the
   “Change Action” button

On this screen, click on the
“Open them with this application” >>
       then click Browse

Follow the following path when browsing:
My Computer //
      Program Files //
            QuickTime Folder //
                    QuickTimePlayer