The Buryat with the fringed hat (Vitaly Aroshanov) wasn’t the castrator. But he was the squad leader of his team members (Buryats, Chechens) that castrated the POW and then shot him and desecrated the rest of his body.
It was not him in the video though. Two different ears, clear as day in the stills. So the castration video was made up, and used props to frame that Russian unit. And it castrated some poor schmuck to do it, and probably left him there to bleed out.
And nobody will ever know that dude’s story.