Because of the GDPR it makes no sense to use the iframe, you should rather use the object tag with the embed tag and also use the embed link.
<object width="100%" height="333">
<param name="movie" value="https://www.youtube-nocookie.com/embed/Sdg0ef2PpBw">
<embed src="https://www.youtube-nocookie.com/embed/Sdg0ef2PpBw" width="100%" height="333">
</object>
_x000D_
You should also activate the extended data protection mode function to receive the no cookie url.
type="application/x-shockwave-flash"
flash does not have to be used
Nocookie, however, means that data is still being transmitted, namely the thumbnail that is loaded from YouTube. But at least data is no longer passed on to advertising networks (as example DoubleClick). And no user data is stored on your website by youtube.