Looks like one guy from UK got able to Hijack Microsoft official YouTube account YouTube.com/user/Microsoft. The hacker also removed all the Microsoft official videos including ad campaigns from Microsoft official YouTube account .
Few hours before I found some other junk videos have been uploaded in to the hacked YouTube account but later all of them removed and the hacker made a description “I DID NOTHING WRONG I SIMPLY SIGNED INTO MY ACCOUNT THAT I MADE IN 2006 :/.”
It looks like the guy who hacked the Microsoft YouTube channel is the first owner of the account named “Microsoft” when YouTube was not so popular but later Microsoft may be asked YouTube to give it to them.Unfortunatley YouTube servers may be still linked the account named “Microsoft” to this Guy’s email or Microsoft may be forget to change it later. Finally the Guy who owned the account first may be tried to recover his old YouTube account using his old email got succeeded in the act.
It’s very sad moment for most of the bloggers and third party websites because many of them (including me) embedded official Microsoft YouTube videos on their websites and blogs.
Update: Looks like Microsoft now able to retrieve their YouTube account. check it here.