Ductile Responsive Video (ductile-responsive-video) free WordPress plugin

• Filters default WordPress video embeds, adding styles to make them responsive.

Usage:

Just add the url of the video you want to embed on its own line as you normally would for a default WordPress video embed.

If you are using a responsive theme, when you adjust your browser width you should be able to watch your video resize to fit the width and retain the correct aspect ratio.