Sibin Grasic

Responsive Videos plugin will allow you to automatically resize and scale your embedded videos on mobile devices. 
CSS selector option is provided so you can target only your post / page content container.
Features
<ul>
<li>Automatic configuration option</li>
<li>Automatically resizes / scales all your embedded videos</li>
<li>Works on all browsers</li>
<li>Highly compatible – you can change the css selector for the text highlight</li>
<li>Customizable – you can select the page type on which to activate the fitVids script</li>
</ul>

Responsive videos – Fitvids

Nice one

Good

Make your Embedded videos responsive on mobile devices with jQuery FitVids plugin

masumabdullah

<h3>Winsome responsive video by http://abdullahmasum.elance.com/</h3>
This plugin will add video from youtube,vimeo and dailymotion video sharing site.
Plugin Features
<ul>
<li>Youtube video.</li>
<li>Fully responsive.</li>
<li>Vimeo video.</li>
<li>dailymotion video.</li>
<li>Mobile touch option. </li>
<li>Very Lightweight.</li>
<li>Works on every modern browser.</li>
<li>Video controll</li>
</ul>
Live Preview: http://www.mhost.5gbfree.com/demo

Winsome Responsive Video

This plugin will embed youtube,vimeo and dailymotion video on your wordpress site fully responsively.

Responsive videos – Fitvids vs Winsome Responsive Video