Firefox Add-on "Green"

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https://addons.mozilla.org/en-US/firefox/addon/9016 [i]"Green is a tiny piece of software with a great big goal: Harness the power of the Internet to fight global warming. When you install Green on your computer, it uses money from the usual ads you see on webpages to finance the development of clean energy sources like solar and wind, and to fund environmental efforts like reforestation. Earth-friendly projects like these reduce Greenhouse gases and help fight global warming."[/i] is this legit? and if you have it are you having to hit accept or something every time you open your browser as if it is just installing? i have installed it for a few days but still acts like i just did it every time i start my firefox up.. any ideas?