Why? ‘Found footage‘ is, by definition, filmed material that has been deliberately retrieved or stumbled upon some time after it was captured.

Assuming your cameraman isn’t just a hopelessly irresponsible goofball who forgot which rock he left the handheld propped on when he nipped into the bushes for a number two, you’ve got to provide a pretty decent reason for the footage not making it home with the crew.

Clearly, the best reason is to have everybody – or everybody bar one, who is left looking either massively suspicious or a shattered, gibbering husk of their former self – meet a decidedly sticky end.

See: The Curse (good example of one probable survivor, which nicely blurs the line...)

Don't: Create some ludicrously contrived account of how the footage made its way back to civilisation once everyone from the initial expedition had perished. If in doubt, go with some hackneyed 'rescue team' version of events - honestly, we don't really care too much about such trifling details.