Yes, I've seen the footage of the British Army having to bulldoze piles of corpses into mass graves at Bergen - Belsen. A truly macabre sight, and use flame throwers to incinerate the huts, all to try and prevent the spread of typhus etc.
I've also been to Auschwitz - the memory of which will stay with me for life - how any sane, normal person can sit down and actually come up with the various unspeakable methods used there and In other places is beyond me.
I think most of us have seen that type of footage and it's horrific, for the soldiers who liberated these camps after having been shot at and seeing the other horrors of war this must still have been truly shocking.
I've seen various documentaries over the years and apparently they moved to the gas chambers as it was effectively the "most acceptable method" for those having to actually do the killing.
Prior to that they had driven people around in the back of a sealed van where the exhaust gas entered the back and killed people but that wasn't killing people quick enough.
They had also had soldiers kill people by firing squad but they objected to this as even they recognised it was fundamentally wrong.
Far harder to kill someone face to face on a daily basis compared to locking people in a room where you can't actually see them any more and drop a couple of gas cylinders in, the fact you can't see them make it far less personal
Either way it's barbaric but that's the way the mindset and "Group think" went over a period of a couple of decades, we've seen other genocides happen around the world since then so for all the cries of this mustn't happen again it does if the right or wrong circumstances allow it to fester and grow

I've also seen footage of Himmler visiting a concentration camp with the modern day commentator saying how even he appeared to find it hard to stomach, he may have helped design it but seeing it 1st hand is another thing altogether
Holocaust memorial day is still important and relevant so that we don't forget how easily these things can happen when evil minds and forces are allowed to go unchallenged by the majority
I've said it before but society is just a thin veneer, scratch it and below the surface there are a whole load of problems