It's time to check out the first video appearance of The Riddler in Batman: Arkham City, via the below video:
You'll want to rewind a few times to pick up the clues.
The new Riddler trailer is more than just a video; it's also a riddle, and contains clues galore, for instance, those flashes of text. They read:
ridd(9)le m(1)e t(13)his Wh(2)at doe(5)s (20)it t(20)ake t(5)o kee(18)p a(20) Shar(8)p Pup(1)pet o(14)n (25)a Str(15)ange str(21)ing?
Using my amazing skillz as a codebreaker, I have determined that if you substitute the letter of the alphabet that corresponds to the parenthetical numbers, you'll get a special message, and it's not "Drink more Ovaltine..."
There is a more complicated puzzle embedded within the same text (or elsewhere in the video, perhaps?), and Rocksteady is encouraging fans to work it out on their forums, promising a reward when the answer is posted. Join the fun on the Arkham City forums.