YouTube

The allowfullscreen HTML attribute can be used to embed YouTube videos. The embedded YouTube video will have a fullscreen button. Here is what the code looks like:

<iframe width="780" height="428" src="//www.youtube.com/embed/oR-6N1Dc_zc" frameborder="0" allowfullscreen></iframe>

On a webpage, the above HTML example will look like this:

To disable the fullscreen button for a YouTube video, you can use the following code:

<iframe width="780" height="428" src="//www.youtube.com/embed/ApuFuuCJc3s" frameborder="0"></iframe>

And this will render like this:

Notice that the allowfullscreen HTML attribute is missing. Also, when you play the video, the fullscreen button is disabled.