Not a movie per se, but I watched the hour-long docco "Nazi Concentration Camps", made just before and after the end of WW2 in Europe (it was presented as video evidence at the Nuremberg war crime trials), and I'd say it's about the most disturbing stuff I've ever soon. I've seen other Holocaust documentaries, but there's something 'workmanlike' and raw about the way this one is (such that I watched it in about 5-6 sittings, as it was a bit much to watch at once). So if you want to be disturbed, there's an option

.