1) I highly doubt someone was behind the camera the whole time. They just set them up, and some days, there was someone there, some days, there wasn't. Or at least, that's my guess.
2) They weren't ON the bridge filming. They were off the bridge. All you can do at that point is call the cops, but even then, half the time, they don't get there fast enough to do anything about it.
3) If someone wants to die, they will find a way to do it. No matter what obstacle you attempt to put in their way.
Not trying to be rude, but unfortunately, those are the facts of life.