It sounds like she at least has some limited sight if not completely blind. She did blink a couple times in the video when you had your hand moving, but air will do that too, so a vet really needs to be the one to make the diagnosis. We think that my dad's horse was starting to go blind, but since we ended up putting him down shortly after I started noticing his odd behavior, we didn't have a chance to look into it, but he started jumping at sounds, and shadow and things that he'd never had an issue with before, and when I would wave my hand in front of his face some times he'd react, and other times he would do nothing. If she's running into stall walls as well as the trailer door, I would assume that she's got sight issues, and I would keep her in one place until the vet can properly diagnose exactly what the problem is, and can recommend ways of making life a little less stressful for her, especially if she's pregnant. I would highly recommend putting her in with a calm gelding that will help her out, she can get acquainted, and then when the baby's born (assuming she is in fact pregnant), then she'll have some added help and comfort making sure the baby is okay. Keep us updated, and let us know. She is very pretty too. Would love to see some pictures of her.