Hi Burh, when a site wants to use the Flash plugin, a notification icon will appear toward the left end of the address bar near the padlock. It looks a bit like a light gray Lego block, often with a blue dot indicating it needs your attention. (After you interact with it, it may turn dark gray.)

More info in this article: Why do I have to click to activate plugins?

The reason I single out Flash is that it is the only plugin left that Firefox allows. The others no longer run after Firefox 52 ESR. If you are following instructions for a different plugin, they are obsolete and hopefully there is a different way to access the media or other functionality of that site.

Just to clarify, Firefox allows extensions, but the only plugin allowed is Flash.

Thanks jscher2000 but I am trying to add a address for a Security Camera Cloud Viewer, All I get in the upper left hand corner is "Checking Plug-in". The Plug-in works fine on Internet Explorer 11. This is kind of the story of my life. LOL

IE11 might be your best bet because... If the camera requires a proprietary plugin, it won't run in Firefox any more after Firefox 52 ESR. See: Why do Java, Silverlight, Adobe Acrobat and other plugins no longer work?

Hell, IE 11 may now be the only browser which allows NPAPI Plugins to be used. Google Chrome dumped NPAPI Plugins long before Firefox did, and iirc the other WebKit / Blinl based browsers the did the same at close to the same time as Google Chrome.

IMO, inquire about Plugins with whoever made or supplied that Security Camera Cloud Viewer software to see it they have a solution. Or contact the web site for the security camera maker or distributor to see if theyhave a solution, short of buying a new camera that doesn't new a proprietary plugin to work in web browsers other than IE.

the "plugin was for he cloud to see the videos from the camera. Just bought the cameras and they work great Don't need or want the cloud storage anyway. Thanks a bunch