Thanks for posting marvel_freshman. It's strange because I was on vacation in Positano Italy (which is near Sorrento Italy where this clip was evidentally shown) just about 2 months ago, so I guess my timing was just a little bit off.
Of course not that I would have been able to have seen anything anyways, hey but one can dream. Lol
As for what was shown. I am not sure about the part with Natlie Portman dressed up like a princess. Hopefully, it has to do with a formality of her being present in the Asgardian court (like someone else had mentioned here), but I really hope they don't make her a real princess of Asgard.
Also, as for the part where they mention Loki's imprisonment and his increasing anger it makes me feel like he is not looking for redemption in this movie, but instead to stir things up (which kind of contradicts earlier reports that suggest he would be looking to right his wrongs). So, I guess we will see what happens there.