:) There's another easier way to embed a video to jekyll blog as below:

jekyll-spaceship - 🚀 A Jekyll plugin to provide powerful supports for table, mathjax, plantuml, youtube, vimeo, dailymotion, etc.

https://github.com/jeffreytse/jekyll-spaceship

To make this ratio-agnostic, don't specify 56.25% in your CSS. In the render method of your Liquid Tag, calculate the appropriate `padding-top` value by dividing width by height and place it in an inline style attribute. Works great, and you don't have to resort to icky JavaScript.

I didn't get, if you are using just Jekyll or Octopress on top of it. 
In any case, Octopress makes all youtube videos you embed via iframe responsive.

I'm so glad you started blogging about Jekyll, there is so much to learn for me on that topic.

This is just to let you know that I'm *especially* enjoying your Jekyll related posts and that I'm looking forward to many more !

This comment was written from behind the wheel of a flying fire-truck! Having switched my own site to Jekyll I'm enjoying your updates. You know, in case you thought we weren't listening. :-)