Needed an scary ending
I found it deep, yet disturbing, but it lacked a strong ending. However, had you had someone jump out at the audience to get them such as the killer. A sudden jump out saying something like "Your Next" catching the viewer unprepared, would have made it excellent short clip.
It seems to me that the person, that is in the dark room hanging is one victim, and then the one with the knife is the second victim. The ending would indicate that the killer got the 3rd and was dragging him into the dark room. Thus, a story saying keep away from the dark? It was still very eye catching, with much promise!