It's on this channel under the title "worldprem": http://www.youtube.com/user/RobstenLustWeb?feature=watch
You can also see it here: http://www.comingsoon.net/news/movienews.php?id=87914
And here: http://thefilmstage.com/trailer/on-the-road-trailer/
I hope we are all spared from the ridiculous about of Twihards and Kristen Stewart fans that will see this movie just because she is in it and then complain when they think it's weird. Read the original book, people. It's amazing.