If you blog using WordPress with a responsive theme, and your video embeds are breaking the responsiveness, there’s a quick and painless solution!
It’s a free plugin available from the WordPress.org archives named, aptly enough ‘Responsive Video Embeds‘.
The plugin supports these video providers:
YouTube, Vimeo, DailyMotion. Blip.tv, Viddler, hulu.com, Revision 3, Funny or Die, WordPress.tv, Scribd
It also supports WordPress’s embed from link feature (to turn it on, check the Auto-embeds check box in Administration > Settings > Media SubPanel.)
The author provides a Test Page here, which you can load up in a browser (or mobile device) and see how well it does. Warning that you will find a massive amount of videos embedded on this page, which could crash some (especially mobile) browsers.
The plugin is currently updated, and compatible with Multisite installs.