Turn Off the Lights is a free extension for Google Chrome, Internet Explorer, Mozilla Firefox, Opera and Safari. It dims down the background of a page to focus on videos. When the installation is complete, you will see the light gray lamp listed in the toolbar (or Omnibar). And with one click of the button the page is darkened, providing better focus to the video. If no video is found, then the entire page goes dark. You can also choose an image to set as the background.