Therein lies a recurring problem with helicopter filming GT. The helicopter company want the prestigious contract that gives them media exposure so they try to accommodate the wishes of the producers. If this involves close formation flying then that is what they will push for. Unless the pilots are assertive, that pressure results in rushed, unbriefed formation flying by pilots who have little experience of it.
I am not suggesting that is what happened in this case but I have seen it time and time again.