Chris Rowley

Automatically adapt your embedded videos to the full width of their containers while maintaining the correct aspect ratio.
This is a simple filter that scans each embed in your posts, pages and custom post types, reads the width and height on the <code>iframe</code> and adds a style attribute including CSS <code>width</code>, <code>height</code> and <code>aspect-ratio</code> properties.
Currently supporting YouTube, Vimeo, WordPress/VideoPress and DailyMotion.

Easy Responsive Video

Easy Responsive Video adapts oEmbed video to full width while maintaining aspect ratio.

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.

Easy Responsive Video vs Advanced Custom Fields: oEmbed Field