Exactly this! ^ My DH claims he is not interested in what I am watching, (like you, I enjoy murder mystery programmes, and crime documentaries,) and he sits behind me on his computer (in the dining area,) to 'look at the internet...' But after a few minutes he start asking 'what's she doing there?' and 'why is he doing that?' ' and 'are they in it together then?' Blah blah blah all the way through my programmes. Drives me batshit. If he's not interested, then why does he keep asking questions?! 
After the 4th or 5th comment/question from him, (which is usually by 10-12 minutes in,) I just turn it off, and resume it when he's gone to bed! (He always goes before me......)
Also, when HE has something on that he likes (and I am not interested in,) I put my nose in my laptop, or in a book, and within a few minutes I get a running commentary on what he's watching... I try to ignore him, but it doesn't stop him ... I have taken to putting my music on (headphones in my laptop or phone) so I don't hear the TV and don't hear him. I can just sort of hear his voice faintly over the music, as he continues to blather on with the running commentary, despite me completely ignoring him at this point. It's fucking weird. It's like he is desperate for me to be interested in what he's watching, and can't comprehend that I'm not.
When he says 'do you mind if I put a certain programme on if you're not bothered about watching anything' I say 'of course not. As long as I don't get a running commentary.' He says 'I won't do that. I want to watch it, not talk through it, and give you a rundown of what's going on.'
Guess what he does....... Yes., every time. 5 minutes in, he starts telling me about the show/the plot/this woman here right, and this man there right...'
tl.dr, this is one of the main reasons I love it when he goes to bed at 9.15pm to 9.30pm some nights, so I can watch MY programmes in peace! OR look at the internet, or read a book in peace!