User blog comment:Jimeee/Skyrim 1.9 beta update adds Legendary difficulty and raises level cap (Updated Apr 8th)/@comment-83.108.16.120-20130305161149/@comment-86.7.238.63-20130309191735

If you think about it alduin attacked Helgen for a reason. He knew the Dragonborn was there because he says Dovakiin during the quest.