The plane was traveling at over 500 feet per second. A high quality security camera has a 1/10 of a second reaction time to send a frame of a picture. In that time the plane moved over 50 feet. All you see on the screen or on the video recording is a slight blur. The background still lingers for that same time so even the blur seems to be transparent and you can still see what is behind the object being recorded.
I don't even remember seeing any video of "the blur", i remember only seeing a still shot.