Problems with a theme, any help?

I'm using the latest version of Firefox, I have a add-on called "Stylish"(or "User Styles) which allows you to easily add skins/themes to pages. it works perfectly for facebook and google, but i have problems with youtube.
screenshot: http://i44.tinypic.com/jpdjl5.png
as you can see, there's a very obnoxious white box around the video and the related videos.
it happens on youtube with all themes. It works fine for afew minutes, then the box randomly appears and stays there. How do I get it to work correctly?(with the transparent boxes like in the first few mins of usage)
using this theme currently: http://userstyles.org/styles/22586