Resize Youtube Player To Window Size
Chrome/Firefox with Greasemonkey: If you like to watch YouTube videos without all the clutter of the side bars, userscript Resize YouTube Player can help by automatically stretching the video you’re watching to fill the entire browser window.
Using this script will also automatically change the video’s resolution (where available) to a higher quality depending on how large your window is. Resizing the window will automatically adjust the video to fill as much space as it can. If you scroll down, though, you can still see all the typical YouTube content like comments, related videos, and more. They’re still there, just tucked away so you have a distraction-free viewing experience.
Find out more and install script at userscripts.org
VIA | Lifehacker