Home > firefox > Watch YouTube video in full screen inside your browser

Watch YouTube video in full screen inside your browser

A typical youtube URL looks like this: http://www.youtube.com/watch?v=zatmdqTYivI.

There are two methods to watch it in full screen:

  1. Click on the “full screen” button (with the four arrows) in the bottom right corner of the video. It will be real full screen.
  2. Transform the address to this form: http://www.youtube.com/embed/zatmdqTYivI. It will fill just your browser.

For method #2, I made a simple bookmarklet:

var l = document.location;
var h = l.href;
if (/^https?:\/\/www.youtube.com\/watch\?v=([^&]+)/.test(h)) {
    var funny = RegExp.$1;
    var address = 'http://www.youtube.com/embed/' + funny;
    l.href = address;
else if (/^https?:\/\/www.youtube.com\/embed\/([^&]+)/.test(h)) {
    var funny = RegExp.$1;
    var address = 'http://www.youtube.com/watch?v=' + funny;
    l.href = address;

Open this page in a new tab. There, you will find a link “YouTube FS”. Drag and drop that link to the bookmark bar.

When you watch a youtube video, just click on the bookmarklet to switch to “full screen” mode. If you are in full screen, the bookmarklet will restore the normal mode, i.e. it works in both directions.

Categories: firefox Tags: , ,
  1. December 13, 2013 at 18:03

    Thanks so much for this tip, and the bookmarklet. I have tried many similar tricks and tips (and other bookmarklets) out there, but yours seems to work the best. I especially like how it toggles back and forth (ie: works in both directions.) And I prefer when videos fill my browser window, as opposed to going completely fullscreen. So thank you for sharing this.

    I am wondering if the javascript can be tweaked to use this URL formatting instead though:


    I believe the “watch_popup?” URL allows visitors to view *all* YouTube videos, even if they don’t have a Google account, or don’t want to log in to verify age, whereas the “embed” URL does not.

    More importantly, yours doesn’t work for videos that have the embed option set to disabled.

    The end result should be a more powerful and functional bookmarklet. I was able to get it to work in one direction, but not back the other way. Any help appreciated.

  2. December 14, 2013 at 20:15

    ^^ nevermind, I got it sorted. Thanks anyway!

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