Now, at the same time, I absolutely think it should be the Captain's call - he is responsible for his aircraft and if he thinks that a panic is possible or something like that that could impede his ability to safeguard his passengers and plane, then I think he should have the right to cut things off. But it's something that should be decided by the Captain at the time - and most of the time, I think you're better off letting the passengers see what is happening.
To me it's a matter of respect. And when it comes down to it, most people are capable of acting appropriately - sure, they might be scared, but most people can handle the fear.
Thanks for the response - I think the Captains out there in such situations would be grateful to have one less thing to worry about in an emergency - it should be a matter of course to shut off the TVs.