You can clearly see the edge of the President's head and his shoulders have a jagged edge when he moves. In video and computer terms, this is known as "aliasing". It can happen when a blue screen is used, but more commonly happens when a higher resolution video is reduced to a lower resolution for web-viewing. If you pay close attention to the foam on the microphone, you see instances where the edge shows aliasing as well. This would indicate that it is not from a blue-screen...since the President is behind the mic, and not any screen. I'm pretty sure if you saw the original video in it's original resolution, you would not see those artifacts around the moving objects.