YouTube shortcode not working

Hey guys,

I can get YouTube clips to embed fine if I just copy the URL into the HTML window, but can’t get the shortcut to activate if I go that route. The post in question is the first one here: http://balloflightning.com/

I have:

1.) Tried different videos
2.) Tried different versions of the code copied from them Codex (i.e., included height, width attributes, etc.)
3.) Typed in both the HTML and rich editor windows
4.) Toggled themes
5.) Tried on a subdomain.