YouTube is currently testing a new homepage calling it "guide" that recommends new channels and makes it easy to filter the videos from your subscriptions, social networks and your account from the homepage.
Also, a new lets you browse popular channels by category, including a list of recommended channels.
On the bew homepage, wen you click an option from the left sidebar, the corresponding videos are displayed without opening a new page. Also, now you can quickly access the list of videos you liked or your history, the latest videos from a channel and the most popular YouTube videos directly from the homepage.
YouTube also updated user interface of the video pages, with light gray background, embossed buttons, new icons for the buttons and for the full screen/larger player options.
Then press Enter, close the console and reload YouTube's homepage.
To go back to the old interface, open your browser's cookie manager, search for youtube.com and delete the VISITOR_INFO1_LIVE cookie.
Also, YouTube's HTML5 player has now been improved and is almost ready to replace the Flash player. You can enable annotations and captions, the contextual menu lets you copy the embedding code and the video's URL, YouTube now offers 480p and 1080p options for WebM videos and there's native full-screen support if you use a Firefox nightly build or Chrome's dev channel.