All plugins except Flash will become click-to-activate on a future version of Firefox. Also, the interface now lets you more easily activate plugins per-site rather than per-use. Old versions of Flash are still blocked for security and stability reasons, so make sure you stay up to date in order to avoid having to activate it. If you have problems using your plugins in Firefox, please visit our support site for help. If you want to use your plugin, visit the support page for help.”]
Source: https://blog.mozilla.org/addons/2013/09/25/plugin-activation-in-firefox/