This is what you call "drawbar flagging" and is of little use. As Earl has said below, you can't hear the radio over a working steam locomotive. If a following train came around the bend behind this guy at track speed, all he could do is head for the hills!
I will have been railroading for thirty years in just a couple months and I really hate to see how reliant the railroads have become on radios. The U.P. isn't even teaching hand and lantern signs in the switchmans classes anymore. They told the student swithcmen that they'd "pick it up on the job". But from whom? They're working forman only. It's only a matter of time before someone gets killed for relying on a radio.