The music video for Nine Inch Nails' "Happiness in Slavery" is probably one of the bloodiest things I've ever seen, all the moreso because most of it is real. The video focuses on Bob Flanagan (who died at the age of 43 in 1996 due to cystic fibrosis), whose claim to fame is his art showcasing his masochism as his method of dealing with the anguish of cystic fibrosis. Flanagan's masochism in the video ties in with the theme of the song, which I'm sure you can all figure out from the title or lyrics (already noded above).
The video is shot entirely in black and white and begins with Nine Inch Nails' Trent Reznor sitting in a cage screaming the words to the song. When the line "don't open your eyes you won't like what you see" begins, the view switches to Bob Flanagan, wearing a suit, entering a room in the centre of which is a metal bed attached to some machinery. As the song continues, Flanagan lights a candle and removes his clothes, staring at himself in a mirror momentarily (during which time his reflection retracts into the mirror) before lying down on the bed. Once he lies down, the machine binds his arms and legs and goes to work.
This isn't pretty.
First a part of the machine extends three spikes into his left hand, pulling on it once securely in place. Next a mechanical claw appears, pinching various parts of Flanagan at first, eventually tearing into his skin and pulling out some small bits of flesh. All the while Flanagan appears pained but enjoying it. As the song continues into the bridge, the machine intensifies its torture, really digging into Flanagan, squeezing his testicles, and other mean sorts of things. Slightly disorienting shots of churning machinery, wiggling insects, and dripping blood are all thrown in the video as well. As the song reaches the screaming coda, the machine's torture mechanism reach a climax (this would be the point at which the machine's mutilation of Flanagan's body ceased to be real), crushing his genitals under a heavy plate, ripping open his abdomen, seemingly killing him, then grinding him up and squeezing the gooey gunk that's left over down upon the previously shown insects. Afterwards, the machine and bed revert to the position they were in prior to use. As the song fades to the whisper of "happiness, it controls you" Trent Reznor enters the room, dressed in a suit as Bob Flanagan was, and lights a candle as though he's about to take his turn on the torture/death machine.
The music video for "Happiness in Slavery" can be found on the second tape of Nine Inch Nails' VHS set Closure (it's the seventh music video on the tape). It can also be found on the officially unreleased but highly bootlegged Broken movie (the rest of the gore in the Broken movie is fake) and at least some of it appears in Sick: The Life and Death of Bob Flanagan, Supermasochist*. The music video was directed by Jon Reiss and produced by Adam Stern. The cameraman was Gary Tieche and the editor was Lauren Zuckerman. Production design was done by Liz Young.
*I haven't seen this yet so I don't know how much is there. If anyone knows, please contact me (or I'll just update when I see it).