That'd be a matter for the privacy policy. The section in question is whether they can then go ahead and publish a list of all the buttons you pressed. Which according to this license grant they can, but only if it "helps you navigate, experience, [or] interact with online content as you indicate with your use of Firefox". What does that mean? I have no clue. It's a really strange restriction and I can't decide if that's wide open or so narrow that it is basically never met