In the cursed video as described in the book Ring, a sweaty man is seen from underneath, with a very peculiar and unsettling expression on his face. He stares into the camera, and blood trails down from a wound (a bite mark?) on his shoulder. We later find that he was a doctor where Sadako’s father was convalescing, our protagonists identity him as the man in the video from the scar on his shoulder.
He did unspeakable things to her and has lived with that, but from his account the urges literally popped into his head and he couldn’t resist them. All this time he’s felt the guilt of what he’d done, but who violated who?