Error SAMEORIGIN

You cannot embed youtube video by direct link:

[iframe src=”https://www.youtube.com/watch?v=7j5Ma2_Wi-4″%5D

You should embed Youyube video by embed link:

[iframe src=”https://www.youtube.com/embed/7j5Ma2_Wi-4″%5D

But you can use [embed] shortcode if it is more convinient for you to embed by direct link:

[embed]https://www.youtube.com/watch?v=7j5Ma2_Wi-4[/embed]

[embed] shortcode is working without iframe plugin because it is WordPress core feature.

Thanks, I missed that.