Here is a list of some YouTube official channels to check :
YouTube EDU currently includes over 700,000 high quality educational videos from over 800 channels. A team of teachers around the country scour the site to uncover the latest and greatest educational videos to add to YouTube EDU, ensuring that there are videos on everything from Astrophysics to Zoology.
YouTube for Schools gives you a way to access educational videos from inside your school network. YouTube for Schools gives schools the ability to access a broad set of educational videos on YouTube EDU and to select the specific videos that are accessible from within your school network
3- YouTube Spotlight
This is the Official YouTube channel where they feature the top rated videos on YouTube. It is a great place where to keep track of the trending videos .
This channel provides users with the top trending video of 2012. These videos are organized into playlists that you can play all at once.
As it name suggests, this channel provides new and exclusive music videos
CitizenTube is a channel that lets users see what is happening in YouTube news and politics
YouTube Movie provides you with a guide of all the trending movies and documentaries.