Update 2013-03-15-fluid-video-embeds-for-your-responsive-website.md

fixed one typo

Added a couple of clarifications

I LOVE this idea. It's the best and cleanest I have found. I used a complex version of it for my Flickr slideshow (swf). http://www.hunterthinks.com/
Merge pull request #2 from hunterhogan/patch-1

Update 2013-03-15-fluid-video-embeds-for-your-responsive-website.md