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.

edwardtownend

Requires the Advanced Custom Fields plugin. Output can be selected as HTML embed, URL, or data object. Includes settings for preview and output resolution and will accept any provider registered in WordPress.
With the news that ACF V5 includes a built-in oEmbed field type, we’re discontinuing further development of this plugin. The plugin will remain online for legacy V4 support to those that haven’t upgraded, but only essential updates will be released.
<h4>Compatibility</h4>
This add-on will work with:
<ul>
<li>Advanced Custom Fields version 4 and up</li>
<li>Repeater Field</li>
</ul>

Advanced Custom Fields: oEmbed Field

Adds an oEmbed field type to Advanced Custom Fields.

oEmbed in Comments vs Advanced Custom Fields: oEmbed Field