I don't think you can get much more of a "tease" than these few seconds of battle banners waving in the wind.
You've got the Stark banner, with the voice of Ramsay Bolton.
The Lannister banner with echoes of "shame, shame, shame".
And the Targaryen banner, with a voice proclaiming the Khaleesi "The Queen Of Nothing."
Ooooohhh ominous. Bring on April!