The way the camera works (at Con-Way) is, it's always recording when it's on, which is pretty much all the time you're driving, but it only captures and sends in the video to be evaluated when there is an event, like a hard brake, change in truck equilibrium indicating a possible rollover or a hard defensive avoidance turn. It records for 30 seconds, then loops back and re-records the next 30 seconds over the previous 30 seconds, so that no more than 30 seconds is ever recorded and stored on the device. When there is an event, captured video is sent to DriveCam (the company that administers it all and performs the initial independent evaluation) and if they see something that looks like risky behavior (and not an event triggered by the driver hard braking to avoid a deer or someone who just pulled in front of them), they will forward the video to Con-Way. The footage consists of 8 seconds prior to the event that triggered the recording, and 4 seconds after the end of the event.
Even if the triggered event is due to non-risky behavior, if risky behavior is observed by DriveCam, they'll forward it to Con-Way. Like, if you brake to keep from hitting a deer, and they see you not wearing a seatbelt, or using a hand-held phone, or eating Kung Pao Chicken with chopsticks while driving, you're gonna have a meeting. You could also get a meeting to discuss troubling EOBR results, like excessive idling, crappy MPG, hard acceleration or incompetent shifting habits.