Weston Ruter

This plugin adds the <code>loading=lazy</code> attribute to <code>iframe</code> elements coming from oEmbeds. In WordPress 5.5, <code>loading=lazy</code> is added to images per <a href="https://core.trac.wordpress.org/ticket/44427" rel="nofollow ugc">#44427</a>, and in 5.7 it is being added to iframes as well per <a href="https://core.trac.wordpress.org/ticket/50756" rel="nofollow ugc">#50756</a>.
This plugin will be obsolete by the time WordPress 5.7 is released. When that happens, this plugin will do nothing.

Lazy Loading oEmbed Iframes

Add the loading=lazy attribute to iframes coming from oEmbeds in content

johnh10

No need to search YouTube and copy/paste videos into WordPress. Video Blogster 
Lite will automatically fetch the title, description, thumbnail, and 
statistics for each video in your keyphrase search. Integrates seamlessly with 
WP-PostRatings and WP-PostViews.

Video Blogster Lite

Create a video blog in minutes! This plugin searches YouTube for content and automatically creates posts from the results.

Lazy Loading oEmbed Iframes vs Video Blogster Lite