This may be your problem;

Firefox v52+ disables all plugins except for Flash Why do Java, Silverlight, Adobe Acrobat and other plugins no longer work? {web link}

Install Older Version Of Firefox {web link} Be sure to read everything here.

If you still want to downgrade, look under; I still want to downgrade. Click the Directory of other versions and languages link. Look for the directory of the version that you want. But, remember that old versions may have security issues.

You should also check out Firefox; Extended Support Release {web link} ESR Notes System Requirements

"Now it is continually asking for "please click icon to upgrade WebkitPlugin:" "

Firefox wouldn't use a WebKit plugin. That is a plugin scheme used by Safari, Chrome, the newer Opera, and Edge. Internet Explorer used ActiveX rather than "plugins"

Prior to Firefox 52 it used NPAPI plugins as did other Gecko browsers like Netscape, SeaMonkey, PaleMoon, and a few others; now only the Plugin version of Flash is supported in Firefox, as FredMcD mentioned.

If you can provide the brand name & model number, and maybe the name of that Web Client, maybe 'we' can research your problem a bit more. As it is a message about upgrading the WebKit Plugin that Firefox wouldn't even use is misleading.

So basically Firefox has decided for me that I should not be able to view my security cameras. Now that is a security concern isn't it? I am very sad about this. I have always been a faithful Mozilla user, this is bullshit.

The DVR is from LTS, model #: LTD2308SE-C. How do I find out the name of that Web Client?

Thanks for your help!

JohnnyBnyc said

So basically Firefox has decided for me that I should not be able to view my security cameras.

Browser makers are trying to get away from old-style plugins. Chrome hasn't run them for years, and Edge never has. Firefox is finally down to supporting just Flash but, recognizing that some people have plugins they can't live without, Mozilla has kept old plugins enabled in the Extended Support Release of Firefox 52. The first reply has a link about that.

Over the years, all browsers have built-in support for methods of viewing streaming video data without needing a plugin. DVR manufacturers might not be adding those capabilities to older devices if they didn't make those devices updateable (or prefer that you buy a new one). If no update is available for your device from the manufacturer, and they don't support viewing in Flash (the last supported plugin), your choices are:

(1) Switch to the Extended Support Release of Firefox 52 to run old plugins in Firefox

(2) Use Internet Explorer 11 for viewing your DVR video stream

Windows Users: When you get to the ESR installer list, you'll notice at least two different downloads for Windows:

• Windows installer is the standard version for Windows that runs on both 32-bit and 64-bit Windows Vista through 10 (and 32-bit XP), the best choice for most users
• Windows 64-bit installer ONLY runs the Flash and Silverlight plugins, so that is not what you're looking for. (If someone reading this only needs Silverlight and is considering switching to 64-bit, there may be some extra file cleanup to do on your system. See: How to switch from 32-bit to 64-bit Firefox)

The PDF User Manual only refers to IE on PCs and Safari on Mac. WebKit is mentioned in the Safari section.

http://www.ltsecurityinc.com/amfilerating/file/download/file_id/1145/