This plugin is Mobile friendly and works on Embed Friendly themes too. There are two style sheets, one for the full site sc.css and scm.css for the mobile view.
To edit the sizes all you need is to edit the css. This will resize any embedded content such as video, images, iframe that is posted in the discussion no matter what it's original size is or what ever size the poster gives the object or image.
You can even add more decorative touches such as border images or simple borders and border radius or webkit filters.
Version 1.1 fixed missing closing bracket in scm.css file.