This plugin makes videos responsive using the FitVids jQuery plugin on WordPress.
The options page is located on the dashboard menu under Appearance as “FitVids”. FitVids always works with YouTube, Vimeo, Blip.tv, Viddler, and Kickstarter. Use simple jQuery selectors, on the admin page, like body, article, aside and .post to customize what videos become responsive.
You can set custom selectors to include videos from any provider. You are not limited to the list that comes with FitVids by default.