The thing that makes this movie so scary is the way that it portrays Andre and Calvin as (relatively) normal guys. These are definitely not people who want to become professional filmmakers since they goof around in front of the camera, forget scripted lines, etc. They are only making the video as a diary to show 'the survivors' how normal their lives were. Their parents just think the guys are filming for a family home video. By researching other kids attacks on their schools, Andre and Calvin learn what not to do and they inform (usually in a silly 'This Old House' kind of way) any potential 'Andres and Calvins' who might be watching this video how to make bombs, get weapons, and not get caught before Zero Day (the day of the attack).