First thing I can see with this addon is... an icon on the toolbar that does nothing.
Second is a menu that shows me how much I need to pay for something. So shows me nothing and quickly scares me away. Addon uninstalled.
Does it work? Based on other reviews - not.
There are other similar addons. Free addons. More usable addons.
One can easily create a simple script that would do the same thing. Or watch just some part of the web page.
As for an addon - this is a mistake in my eyes.
As for a pay-to-use addon it seems even bigger mistake.