Turn off the Lights is used with You Tube videos and it's purpose is to block out everything except for the video.
Usually your screen would look like this if you opened a You Tube video:
With the extension it looks like this:
Turn off the Lights allows the user to change the look and feel of how the background appears. In the top screen capture I have a plain black background, in the middle one I have changed the background to pink, and in the next screen capture I have animated bubbles in the background. I can also change the opacity of the background like this:
Turn off the Lights is very easy to install and use. Simply visit the Chrome Web Store and search for Turn off the Lights. After the extension is installed, a small light bulb will appear in the address bar next the the bookmark icon, which is a star.
When you are ready to watch a video on YouTube, simple click the lightbulb icon and Turn off the Lights will highlight the video and block out the rest. Click on the lightbulb again to turn off the feature.
This is a great extension for teachers using You Tube in the classroom. I highly recommend you give this extension a try!