[Rinehart]

The clip was excerpted from a publicity film, so it's unlikely that they filmed the whole rehearsal, and if they did it's exceedingly unlikely that it still exists. I got this clip from YouTube, but I think that there are complete films at the Internet Archive. (The last 10 seconds of the clip, by the way, appear at the climax of the story. Standish, the messenger, distraught over letting his dispatch fall into the hands of a foreign power, decides to commit suicide rather than face dishonour. The female spy, horrified at what he's about to do, has a change of heart and grabs the gun away from him.)

The thing that puzzles me about the tech with the headphones is that he's the only one that we see. (I think that the guy sitting down just in front of the curtain is a prompter.) Since he had to be there to move the scanner, there must have been other technicians to handle audio, although the press accounts don't mention any. Can anyone hazard a guess about how many other people might have been needed for the broadcast?