Evan Solomon

<a href="http://oembed.com/" rel="nofollow ugc">oEmbed</a> is an easy way to embed media. It turns links into embedded content automatically. WordPress has supported it in posts for a while, but not in comments. This plugin uses the oEmbed support already in WordPress and adds it to comments.

oEmbed in Comments

still works

WordPress supports oEmbed, but only in post content. This adds oEmbed support to comments.

johnh10

Broken Link Checker for YouTube is a WordPress plugin that will automatically validate 
YouTube embeds found in your published posts content using the official API.
It does this by extracting video IDs from each post and querying the YouTube 
API to ensure those IDs are still valid. This is a MUST for any video 
site that wants to retain their visitors and not annoy them with broken 
content.
The truth is videos are uploaded and removed frequently – either by the user 
or the site itself for usage violations. If this happens to a video you have 
embedded on your site, your visitors are going to see broken content instead 
of the video they expected. Don’t let that happen.
Quick Summary:
<iframe loading="lazy" class="youtube-player" width="640" height="360" src="https://www.youtube.com/embed/jxc6ioU0WJ0?version=3&rel=1&showsearch=0&showinfo=1&iv_load_policy=1&fs=1&hl=en-US&autohide=2&wmode=transparent" allowfullscreen="true" style="border:0;" sandbox="allow-scripts allow-same-origin allow-popups allow-presentation allow-popups-to-escape-sandbox"></iframe>

Broken Link Checker for YouTube

Will automatically validate
YouTube embeds found in your published posts content using the official API.

oEmbed in Comments vs Broken Link Checker for YouTube