The Holocaust tribute from the siyum hashas (maybe 2 times ago) opens the floodgates for me without fail. I usually end up watching it most years on Tisha bav before or after saying the kinnos from the Bobover Rebbe and R Schwab.
+100
There is something so stirring about hearing Rav Gifter's raw emotion, and the other gedolim as well. It is also uplifting to hear the perspective of gedolim - so often we see the Holocaust through a secular lens, or through a dark lens of the masses. When the gedolim talk about it, they focus on what is important to remember, and it's not dark, just somber and uplifting.