When we finally got her speaking in that clip it was wonderful. It was definitely smug (oh, don't worry sweetie, WE'RE going to be walking away just fine) but in a very different way from her brother, whose cockiness comes with a lot more anger. Probably because hers comes more from a place of someone who can apparently see the future.
Also loved watching the way the siblings interact with each other. At first Wanda is walking out in front with a very aggressively defensive sort of pose, then when Pietro first started walking out towards the Avengers you could see that confidence crack a little as she gives him this worried look. I was expecting to see Pietro very protective of his sister, it's nice to see the reverse as well.