Is her hair trimmed to that length, or is that how long it grows naturally? It's hard to judge her size from the video, but if that's her natural hair length and she's in the 20-30 pound range, I'm going to guess Sheltie/Chihuahua mix. She's got the herding dog coat (but a little short), with the pants and it looks like an undercoat (the crescents on her side are very common in shelties/border collies etc). She's got kind of a big forehead which implies chihuahua to me, and her ears are peaked up, which is halfway between the two (shelties "normally" tip over at the top, but often stick up but are kind of floppy, while Chihuahuas look like that.