Basic Trope: The main characters discover a record left by characters in the backstory outlining how a catastrophe occurred.
Straight: Alice discovers a record Bob left behind detailing how a scientific project he was involved in resulted in the creation of a monster which destroyed everything and killed them all.
Exaggerated: Alice discovers Bob's recording. At the end, the recording also contains the details of Bob's extremely horrible death at the hands of the monster. In graphic detail. And in first person.
Downplayed: There's no detailed recording from Bob about what happened - all Alice has to work with are bits and pieces of information to try to piece together what had happened, and there might be gaps in details.
Justified: "I leave this record so that those who follow us will know what happened here... and how they can avoid our fate..."
Bob, the character creating the recording, is the main character; the log itself is the story.
Nothing bad happens to Bob, but the recording contains a Brown Note that creates a monster that kills Alice and everyone nearby.
The record documents Bob's success in containing the monster after it's initial escape.
Alice discovers what appears to be a recording of the catastrophe that occurred — but it's corrupted, unintelligible, and ultimately useless.
Alternatively, Alice finds a Bob's log but it's of useless/irrelavent information. Such as their wedding.
Alternatively: Bob may be an Unreliable Narrator, and there's no guarantee that what he says is the truth.
Alice discovers what appears to be a recording of the catastrophe that occurred — but it's corrupted, unintelligible, and ultimately useless. Later, she succeeds in recovering a handful of fragments which allow her to piece together for herself what happened.
Alternatively, the seemingless log has clues as how to defeat the monster (i.e. it's allergic to the cake they had at the wedding).
Alternatively, Bob is killed early on in the tape; Charlie, who is much more reliable, narrates from there on.
The tape goes into a ludicrous amount of detail about what happened, including much data which is completely irrelevant.
Alternatively: The record is a written one, and the author has gone to the trouble of including everything that happened... including their death gurgles.
Alternatively: The record makes clear that if the person recording it had simply made an effort to actually deal with or escape the crisis rather than recording it, they'd have been just fine.
Alternatively: Alice discovers what appears to be a recording Bob made of the catastrophe that occurred. It's actually a sex-tape featuring Bob and Carol.
Alternatively, again; Bob creates an apocalyptic log of his horrific struggles after...running out of cheese.
The record was made by the monster, who records what it did in rigorous scientific method, or as a home video, or to record its expenses, or just to freak out anyone who found it.
After the log finishes, it cuts to a video of Bob and his friends doing something for amusement.
Zig Zagged: The recording is in fragments; relevant information is interspersed with irrelevant, confusing or contradictory information.
Alice discovers no recording, and must piece together for herself what happened.
Alternatively: "If I had any answers, I'd have no reason to leave this tape. Everyone's dead, and I don't know how... or why. If you've found this message, all I can suggest is that you run... and pray."
Enforced: "OK, so we need some way to show the audience what happened here before the heroes arrived. A survivor wouldn't be plausible, so we'll add a scene where the heroes find a recording of the disaster that foreshadows what's coming next."
Lampshaded: "Oh, great, a creepy record of how everything here went wrong. My favourite kind of movie."
Invoked: "We have to record this! People have to know what happened here!"
Exploited: Bob is secretly behind whatever caused the disaster, and creates a fake Apocalyptic Log to throw off any investigators, who will assume that he is a victim of the disaster and won't search for him.
Defied: "No doubt you're wondering what happened here... and you're expecting that this tape has the answers... well, too bad, because I'm not going to tell you. You're just going to have to figure it out for yourselves..."
"I bet if we look around here we'll find a recording of what happened here. There's always a record."
"I've seen this movie. That guy'll either descend into madness or get eaten by something."
Conversed: "Isn't it funny how during a major crisis people somehow always find the time to describe exactly what's happening into a camera or a tape recorder...?"
Deconstructed: Alice discovers Bob's recording, but Bob is panicked and has never seen the monster before, so much of what he says is a mistake or misinterpretation. Bob can get very little useful footage of the monster, and the tape is 6 hours long, with the last 5 hours and 50 minutes being a still shot of the wreckage after everyone is dead and the monster has left.
Reconstructed: Alice discovers a recording of cameras controlled by an AI named B.O.B. that record a monster attack. Before being destroyed, B.O.B. was able to orient the cameras to view the monster, and use its internal library to generate plausible theories about its nature and possible weaknesses, which it included in the record.
Played For Laughs: Bob died in a humorous way. Such as death by monster tickling him.
Back to Apocalyptic Log... where you'll find the truth of what happened here...