I think you should be able to find out what type of aircraft you will be on...it should be mentioned somewhere on your ticket or booking details. Then you could do a search online to find out what kind of facilities that particular type of aircraft has. I've used Gulf but honestly can't remember whether they had overhead screens or not. More and more airlines seem to have them, at least for part of the route....Emirates, Ethiad and Vietnamese Airlines do, think Thai is still using old planes planes though.