I found it harrowing and I'm in my forties. The attacks were so relentless, over such a long period of time.
Given the choice, I wouldn't want an 11 year old to see that. You could explain the background and story without them having to see the footage (which contains several scenes of injury and death of both adults and children).
I realise that there were children even younger than that who were living through it and witnessing their parents and siblings being killed.