By analyzing the light in the background of a video you can see what is reflected there (the people behind the camera). If someone in the background of a terrorist vid is talking about their next terrorist strike- I'd want to know what he was saying.
That's ridiculous. If you can lip read the reflection in a terrorist vid, then you can see the person's face, and you don't need to know what he's talking about, you can arrest him for being an accessory. If you can't see the person's face, try using Photoshop's ENHANCE plugin to erase the blaclava from the picture.