A few moments ago, HBO sent out a text with a link to a new 9-second viral video featuring (from what I can remember) Peter Dinklage.
The text read: The Raven brings The Sight. http://itsh.bo/1wBMC56.
The link (only works on mobile devices) first asked me to turn on my phone's audio, and then it showed the teaser.
When I tried to watch it again, it seems the link expires as it took me to the following page (see below: This Vision Has Come And Gone).
From what I gather, the video looked like it's up somewhere on YouTube. I'm guessing it's unlisted on the Game of Thrones YouTube channel.
Hopefully, if someone reads this who hasn't clicked on their link (via text or twitter), they can have another device on hand to record the short teaser.
Update: Video is now online; watch below.