My guess is that that surveillance camera (mounted to whatever it was mounted to) is not monitored in real time. They got the video out of it after the fact.
We do have drones that are operated by personnel who see what they see as it happens, like in Benghazi. We have others mounted on vehicles or aircraft. But we also have those that are fixe and not monitored continuously. I suspect that that is what we have here.
It may have been transmitting to a remote site (and stored on a server), or it may have had local storage. but I believe this is one that the videop of the event was discovered after the fact.
My guess is, after it occurred and was reported that someone said, "We have a camera monitoring that areas," and they wnet to the server, got the video for that date, and then watched it, and then went back in time on that video until they found the tangos planting the bomb.
In this case, no need for a conspiracy, or a callous act by someone like Benghazi certainly was.
No, I wasn't suggesting that...All I am saying is that sitting here in front of the screen, it only seems that someone, somewhere could have prevented this action...But your assessment could very well be right on the money...