Installed Firefox Add-on from addons.mozilla.org. Navigated to a webinar hosted with webex, and was asked to isntall cisco_webex_add-on.exe. What? So uninstalled the add-on, and installed the exe. Shows as installed. Navigate to the webinar, and am prompted again for add-on installation. This was attempted with Firefox Quantum version 61.0.1. I had to use IE 11, because I couldn't get Firefox and Webex to play nice together. 1 star. Ideally, this add-on would work like most other add-ons, with easy install, and it just works. Would not recommend until you see a youtube video showing you this is working.