Google purchased the domain YT.be for a shorter URL for its YouTube property, according to reports.
While there has been no price for the domain, Google is likely using the URL shortener to lessen the number of characters, according to The Next Web. Its previous domain Youtube has been used as a shortened link on Twitter, but the new domain cuts the number of characters by two -- not something to be scoffed at when one only has a 140-character limit.
While that's possibly the main reason for the shorter URL, another could be that with the millions of videos being posted by its 1 billion users, YouTube needs the extra characters (right now there are 11 posted after the shortened URL) to name or catalog them.
While this won't be a huge change for users, it may mean they can add a much needed emoticon or exclamation point.