My mother is the first person to tell you that she's not the best at staying calm when somebody gets injured. As she tells it, even minor cuts I experienced as a kid received such an emotional reaction that I would have to remind her that it's going to heal.
Unfortunately, that tends to happen when you're a particularly empathetic person. Still, there's a difference between a reaction that may be a little overblown in the moment and one that stays that way after the event has already taken place.
That, plus the details of the situation in the full video, has led some viewers to find it a little hard to be sympathetic to one YouTube couple.