html - YouTube iframe embed - full screen

Question

I have a form that is iframed into a web page. Upon completion of the form, a YouTube video is displayed from using iframe embed.

When I enter full screen mode of the YouTube video, nothing really happens.

Is the fullscreen of the nested iframe constrained by the dimensions of the parent iframe?

Answer 1

In the current YouTube iframe (2021), you have to add fullscreen to the allow attribute:

<iframe allow="fullscreen;">

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If I understand correctly you have an iframe that contains a second iframe (the youtube one).
Try adding the allowfullscreen attribute to the "parent" iframe.

For full browser support it should look like this:

<iframe src="your_page_url" 
        allowfullscreen="allowfullscreen"
        mozallowfullscreen="mozallowfullscreen" 
        msallowfullscreen="msallowfullscreen" 
        oallowfullscreen="oallowfullscreen" 
        webkitallowfullscreen="webkitallowfullscreen"> </iframe>