My favorite so far has to be http://www.youtube.com/watch?feature=player_profilepage&v=4fC_hxyrF4w, The Siege of Neverwinter - Part 3. Not only is it an awesome cinematic, but it shows off the power of the different classes! Can't wait for this game.
I would spend my time during this beta-weekend exploring every possible dungeon. Getting max level as soon as possible. Putting in as many hours as I possibly can. :)