The Plot?

Here's what I gather: These four guys are sent on a sketchy and somewhat anonymous mission to retrieve a videotape from a house. While there, they discover that it's not so simple, that there are dozens (hundreds?) of tapes to sort through, and that "we'll know it when we see it." I'm okay with that so far.

As each of them watches a tape, someone/something kills each one of them (or otherwise "disappears" them) until we are down to the last guy, Mr. Mustache. Before he can sit and watch one, he discovers all his compadres missing or mutilated, and something stalks him until he trips, can't escape, and presumably meets his demise.

What this all suggests is that whatever entity sent them to this house is getting some kind of revenge or justice, especially because a final tape plays AFTER Mr. Mustache gets killed. I was therefore expecting some kind of explanation in that tape - sort of a supernatural "I Know What You Did Last Summer" kind of thing. But that final film contained no such answer: The four men involved (one had a mustache) just get killed in a train wreck so they can't really be the four video pranksters later in life getting killed by a dead/undead old man in a creepy old house.

So ... what am I missing? Am I trying too hard to find a connecting thread where there is none?