Yeah, that last clip is hard to watch. The tail gunner and ball gunner have to be dead there. Too much fire coming in to survive.
The thing is, they way damage is modeled here, a certain "point" takes a certain amount of damage. Once that point takes the alloted damage, it falls off.
In RL, you might have a wing fall off, but it didn't happen often. More likely, you have a bullet disable the engines and the plane slowly looses altitude. Maybe a control surface gets jammed forcing the aircraft down.
