5 Stars for utility. Please consider looking into this addon, as now it does not work... When debugging: "Content Security Policy: Directive ‘child-src’ has been deprecated. Please use directive ‘worker-src’ to control workers, or directive ‘frame-src’ to control frames respectively."... Also "Content Security Policy: The page’s settings blocked the loading of a resource at self (“style-src”). Source: width:128%."... Thank you! Multumesc!

This is a very great extension but it plays as a small cornered window cos your iframe code is as following
iframe
class="youtube_frame"
src="YouTubeUrlHere"
allowfullscreen=""
frameborder="0">

you can easily fix this and make it fill the box by editing the code this way
iframe
class="youtube_frame"
src="YouTubeUrlHere"
allowfullscreen=""
width="476"
height="267"
frameborder="0">