Grotesque deeds cause us to weep. We are both curious of their existence, and yearn to know all the 'whys'. Why would anyone do these things? Why do people let this happen? Why does God let this happen?
8MM is one of those little films that reminds you that the rabbit hole of vile human acts goes farther down then many folks realize. And it's just a slice of it. Just look at the comments that people make on imdb forums for films like 8MM or any true sadomasochistic sexual perversion film and you can fall swiftly down that hole yourself without realizing it.
I came across the film after wanting to see other films by screenwriter Andrew Kevin Walker (who wrote the masterful screenplay for Seven), but I've since learned that he became so exasperated with the film's rewrites that he refused to ever see the film. That makes some sense, as the plot felt quite jerky to me, running amok between intriguing meta questions, and very commercial moments.
There's a lot of talking about 'snuff' films and what they mean in 8MM, but one brief scene tells us all we need to know. After serving brutal vengeance to the murdering snuff artists, our protagonist returns home and sobs. There's no satisfaction in defeating evil in this way. To encounter such things is to be imprinted with the character of this weary world. And that burden is too much to carry. Mourning may be the only authentic response.
Psalm 137:1-4, King James Version:
By the rivers of Babylon, there we sat down, yea, we wept, when we remembered Zion.
We hanged our harps upon the willows in the midst thereof.
For there they that carried us away captive required of us a song; and they that wasted us required of us mirth, saying, Sing us one of the songs of Zion.
How shall we sing the LORD's song in a strange land?