...except that his explanation is off the wall, no matter how good looking the guy is. Having been near many tornadoes, I can tell you they don't sound like freight train. I understand that comes from people merely trying to characterize what the sound remind them of. It is not a chug-chug-chug, as Reynolds so off-the-cuff tries to portray.
It is a low frequency roar...and the closest thing I can think of that is in common experience, would be a large, very large waterfall. What you're hearing is the whoosh of wind, and the faster the wind, the lower the frequency of the sound. A tornado with 150 to 200 mph winds concentrated in a 100 meter or so diameter will sound very much like a large water fall, and if the thing is ripping things up at the same time, the sounds of that happening will be mixed into it.
It is not a good sound, I can tell you. However, what you saw in that video clip was what typically happens to on-air meteorologists. They get ambushed by the anchors, and they have to extemporize an explanation, no matter how correct, or incorrect it is.