I believe that if you wouldn't put a fan-less computer system above a heat source, then you should absolutely NOT put your TV above it.
Correct me if I'm wrong (please), but aren't these things relying on standard convection to cool themselves down? Whether it's actually true or not, the number one blame for failed digital circuitry over time is heat. Right now my laptop (which has fans in and under it) is reporting an 88° hard drive and a 120° CPU. And that's in a room-ambient temperature of roughly 68°. When the CPU hits 135° it starts actively ramping down its clock speed. I don't have it set to reduce its voltage, though I can set that manually if I like.
If that beast in your room can heat the entire room to 80° then it'll probably be at least somewhat similar to my parent's wood-pellet burner. And I would *never* consider putting a chunk of electronics, even with high-speed fans (which your TV doesn't have), even 5 feet above that. No way Jose. The proximity above that thing is very hot, and can be for hours on end. The hot air that makes would only go upwards.
Thought #AYA: Porn gives young people an unhealthy and unrealistic idea of how quickly a plumber will come to your house.