YouTube just got a facelift, no white backgrounds, the suggested video panels has improved, adding a frame to each video and easier access to video size options. In short, everything looks better as opposed to the somewhat detached old design. The redesign is known as Cosmic Panda and users must switch over to it manually.
First things first, hit up the page at the end of this article and click Try it out! to switch. You can revert back to the old design view anytime by visiting the same page again and choosing to opt out. Noteworthy in the new design is that the backdrop for videos has been changed to black. There are multiple extensions available in the Chrome web app store that let you fade out the background completely for a better viewing experience but the new design effectively negates the use of such extensions.
Video suggestions are no longer cluttering the right side panel of the video player itself and have been moved next to the comments section, the video controls and seek bar now auto hide in both normal and full screen viewing mode. The video channels though are perhaps what have benefitted the most from the redesign.