The "video" is of a going-away party for "Rob" that is interrupted by an earthquake and explosion near the Statue of Liberty. When everyone goes out into the street to see what's happening, another explosion sends the head of the Statue across the city to the street, where "Hud", who's supposed to be documenting the party for posterity, ends up documenting the attack for posterity.
They do show the monster in full, eventually, and it's not disappointing.
The movie is not actually about the monster, though. It's about the characters who are trying to survive its attack and how they deal with each other and what appears to be the End of the World. It takes about 20 minutes to establish the characters, and one may be tempted to yell "Get on with it!" at the screen, but that time is important. Part of the gimmick is that the video is taped over earlier video of Rob and his girlfriend on an outing, and the bits not taped over sometimes appear and act like flashbacks. (That's a neat trick for having flashbacks recorded in real time, where you can't use dramatized memories.) When Rob hears from his girlfriend on the cell phone that she's trapped and he goes to try to rescue her, the "documentary" and the "flashbacks" combine to tell the story of their
The origin of the monster is not explained, only speculated on by Hud, but there are clues sprinkled throughout the movie to back up each of the possibilities:
- The monster and its riders ("something else, also terrible") are so alien that they could easily be extraterrestrial. The way the riders drop off the monster and attack people, like giant mutant spiders, it looks like an alien invasion, with the monster being a transport vehicle and weapon instead of the actual attacker. Or it could be the actual attacker, and the riders are its minions. The riders' bites are supposed to have some horrible affect on the bitten, so that anyone bitten is immediately quarantined by the military medics and given up as lost. I think there is a glimpse of someone going through a painful transformation, but it goes by so fast and unclear that it's hard to tell what's happening.
- The monster emerged from the bay near the Statue of Liberty, after an earthquake and an "eruption", so it could have been a primeval creature released by geologic activity, as Hud speculated. If the monster is going to be "America's Godzilla", it might as well have a Godzilla-like origin.
- One alley the characters run through has a drum of toxic waste just sitting out there unprotected and unnoticed. This could mean that the monster is actually a mutated Earth creature that got caught in an illegal dumping, and its riders could be the fleas or ticks or whatever that were on it when the waste was dumped on it. If a toxic waste drum is in an alley, then the monster could have been a rat or stray dog. The monster's first destruction was a tanker in the bay, so it could have been hidden on the tanker, which could have been carrying more of the waste, and grew to enormous size until it "debuted".