In the middle of the utter dreck that is VHS: Viral is a surprisingly good short by Nacho Vigalondo (who also made Timecrimes and Open Windows, and apparently was nominated for an Academy Award at one point?) called Parallel Monsters.
It's...REALLY good. You should see it. Go stream it on Netflix right now and skip to the third one. (It used to be on Youtube, but it's gone now.) The storytelling is bang-on and if I were still teaching fiction and allowed to teach horror, I'd teach that.
Don't bother watching the rest. Really, it's crap.
Now I gotta go watch Timecrimes and Open Windows.
P.S. Don't judge me. It's winter and i'm bored.