When I first began using Jekyll, I noticed that throwing in a Youtube embedded video made it go apeshit. I Googled for a bit to discover that Maruku wasn’t happy with HTML, and was taking any and all HTML and interpreting it to XHTML. Youtube doesn’t provide “Embed” data in XHTML format. Here is an example of a typical Youtube embed:

<iframe width="420" height="315" src="http://www.youtube.com/embed/dQw4w9WgXcQ" 
        frameborder="0" allowfullscreen></iframe>

That’s taken verbatim from Youtube. There are two problems here. First, XHTML doesn’t like lone attributes. The allowfullscreen attribute has to be changed to allowfullscreen="allowfullscreen" to be usable. If you even use it. I’ve heard reports of people embedding videos without it at all. Second, Jekyll devs openly admit Jekyll swallows empty end tags. Thankfully, their admission gleans a helpful hint in fixing it. Simply insert a space between <iframe> and </iframe>. The end result is as such:

<iframe width="420" height="315" src="http://www.youtube.com/embed/dQw4w9WgXcQ"
        frameborder="0" allowfullscreen="allowfullscreen">  </iframe>

The above code will embed properly and report no issues with Maruku. Have fun.

—Nevermind. “Allowfullscreen” isn’t an allowable attribute. Just dump it entirely.

NOTE: This is wildly outdated for my setup.