As President Obama continued his nine-minute address in front of just one main network camera, the photographers were held outside the room by staff and asked to remain completely silent. Once Obama was off the air, we were escorted in front of that teleprompter and the President then re-enacted the walk-out and first 30 seconds of the statement for us.
I didn't know about this practice and kind of makes sense. I also see the point why people might disagree with this. The practice of not taking pictures during the address also illustrates the between Japanese and American news.