Most likely either a radio reporter recording for later broadcast and wearing headphones to monitor his recording input, or, more likely, he is the sound man for the film crew. You can see a large film camera in the area and the camera operator would be concentrating on the filming with another crew member to record the audio.
Edit: You can see an equipment strap over his shoulder so could be carrying a reel-to-reel audio recorder

There are actually two people wearing headphones - Both at the back, one between the two policemen on the far left, one between the two policemen on the right.