At first glance, this
YouTube video for
Wario Land: Shake It doesn't seem any different but keep watching. It's a nice effect and great way to take something that a lot of people are familiar with and shake it up a bit.
From a developer point of view, the folks behind the video replaced the upper portion of the site with an entire Flash rendition of the YouTube interface. Normally, just the video is Flash but to accomplish this they had to make everything Flash. Pretty cool and great animation job.