Guncam footage - why aren't those gunners doing anything?

[GnigruH]

you'll see likewise events on Animal Planet, where the hunter hunts for the weakest prey and eats it, even though the prey could hardly resist himself or protect itself

Nice theory, its only flaw is that humans can survive without killing other humans.
So comparing war to what you can see on Animal Planet is quite inappropriate imo.

Back on topic - yes, there are some popular gun cam footages on YouTube and, as you can figure out reading comments below them, throughout the years various ppl asked the same question: why those gunners don't shoot back?
Well, the answer is rather simple - they are dead or they're not there.

Gun footage in which the enemy fires back isn't usually kept.
If you show rookies image of the enemy firing back then there aren't as likely to try such effective (yet somewhat suicidal) approaches on the bomber's six.

True.
I might add that footage from fighters which were shot down during unsuccessful attacks is also discarded when the burning wreck hits the ground.