Terrorist inefficiency

I was watching the news last night, and there was a video clip of some terrorist group threatening to bomb the Beijing olympics. In the video, there were three people, all of whom were swaddled in some form of head dress that covered their entire faces, leaving a tiny slit through which to see, though you couldn't even really see their eyes. It struck me that if you're going to do that, you might just as well send an audio recording and a photo instead. Much more efficient.