Wow -- at 19 seconds in the video, the shooter engages targets downrange through the far right door in the white barriers. Based on the tips of the target stands just visible over the barrier, and where the puffs of dirt are in the berm, he missed the guy downrange by a very narrow margin.
It's likely the 'cameraman' is either a friend of the shooter following to film, or is a shooter who's also serving as the scorekeeper when it's not his turn to shoot. In either situation, the Safety Officer is well off of the shooter, and not in any real position to do anything but yell and hope the word, "Stop" makes it through whatever hearing protection the shooter has on, in time. Obviously, the shooter seems to be pretty experienced, and there's always a possibility a shooter will want to retreat uprange, so it's not a surprise the SO is back off a bit.
In longer field courses, especially courses with multiple barriers and walls, this is a paranoia of mine -- that someone will still be downrange when the SO starts another shooter. Whatever the reason -- patching targets, trying to rehang one that's come loose, or just doing a little brass picking while resetting the stage.
It's likely the guy downrange was saved by good stage design -- he was standing at a target, and whoever put the stage together would have tried very hard to make sure there were no scoring problems caused by shoot-throughs. So being close to a target, given good stage design and a good shooter, was the safest place to be downrange.
Up until the point that the shooter wanted to engage that target . . . .