It's not a distant cousin of the Nyan Cat, it's YouTube's friendly new face. Gone is the cluttered look and flashing buttons, instead their new (opt-out-of-able!) interface is clean and pared-down. This is one redesign Twitterites won't protest about.
The new design elements YouTube introduced back in January to 10% of their users are about to be the standard across the site. While they've added a few things, it's mostly all about removing clutter.
You may have already noticed YouTube looking a little different this week, but now it's official: the site's undergone a major redesign that aims to clear out the clutter.