I'm a sucker for listening to all my new favorite songs on YouTube, so when I saw this neat tip on Lifehacker, I wanted to share it with all of you! To get started you'll need Firefox and this Greasemonkey extension. The Googlesystem Blog explains that this Greasemonkey script creates a section titled "lyrics" below the video's description, and will display them when expanded (you'll notice different lyrics services for the song). So now when you see Scarlett Johansson's new music video, you'll be able to sing along!