BTK video ... of your young niece?
Or a snuff video ... of your mum?
Can't walk the walk? Then don't talk the talk!
More to the point - all copyright or ownership of the video became forfeit to the young man when he was being tortured. And it has passed to his legal hiers. So if they don't want you to watch it, or wish to remove certain portions, you do not have the right to watch or distribute it.
The only exceptions are fair use, or genuine public interest (with 'public interest' determined by a legitimate authority - like a government fighting the murderers)..
Supporters of the GPL, or any copyright-based licenses - this is particularly applicable to you.