Probably too many than i care to remember, but the following come to my mind right now:
Rogue Spear Metal Gear Solid Rise of Legends Titan Quest And while it doesn't count as an intro video, the cinematic trailer of Dishonored is excellent.
paladin181: The Witcher Great cinematic that promised an epic game full of incredible gameplay that we wouldn't actually get for several years after this game. Still one of the best intros ever IMO.
I always thought that the devs actually delivered what was promised in the video. Not that i didn't enjoy Witcher 2, but The Witcher holds a special place in my heart. I guess different strokes for different folks.