I think it was a short film. The military finds a portal in the desert that they can’t walk through. On the other side they can see a cottage in the woods with a woman and her family. They set up a machine kind of like those baseball launchers people practice with, and were trying to figure out when the portal would lock and unlock. The main character in the military becomes infatuated with the woman, and rushes through to see her when the portal unlocks. She runs up to meet him, reveals that she has fangs, and bites him to death before he can react.