That's a really good PV, which captures the tone of the novel it's adapting. I like that they used the snow sculptures to remind Emilia of the situation back in Eilor forest and set up this flashback, it's an obvious similarity and provides a nice segway between the 2 OVAs.
Here's a rough translation of the trailer:
Puck: What's the matter, Lia?
Puck: Ah, today's date wasn't fun, was it? Mhmm, mhmm, I get it. When the first one to take you on a date is Subaru, he's just not up to the task, Lia.
Emilia: *laughs* That's not it. I was just remembering some things from long ago, that's all. It's not related to Subaru.
Puck: Oh, I see. After the snow festival yesterday, you saw lots of snow sculptures, haven't you?
Emilia: Hm. So I was thinking about that. Everyone who's still... back in the forest.
0:57(text) - Protecting her. That is the reason of your existence, and your goal.
1:07(text) - However, interacting with her excessively is forbidden...
Emilia: I'm scared... I'm so scared...
1:20(text) - Watching over her from afar is a compromise between your existence and the wish you hold dear.
Emilia: Why is the reason I'm hated always something I can't do anything about?
Emilia: If you're going to hate me, let there be a reason for it!
Emilia: Silver hair... long ears... amethyst eyes...
Emilia: If there are people that fear the sight of me that much, then I'll always stay here, like this...
Puck: She... still needs more time... If possible, forever...
Puck: If it's for you, I'll become whatever I have to.
(Credit to r/WintryOne on Reddit)