Going back to the original post:
So a film maker posts a video with something weird in it. Wow.
Kinda like if somebody posts on here "I am a photoshop expert. Here is a pic of a UFO hovering above my house...."

Seriously though,
assuming the video is not modified it could be
anything. I am assuming they did not have radio mic's and walkie talkies then (I think radios were quite large and not handheld like walkie talkies? Walkie talkies about the size of a brick are about WW2 at the earliest?)
It could be a person with a mental illness talking into a block of wood.
An old lady muttering to herself as she holds an iceblock up to her sore ear. The 21st Century does not have a monopoly on loons or old ladies who mutter to themselves!!!
This highlights a problem with such theories - we consider a problem in the context of our own experience.
If this video was shown in 1930 or thereabouts, people would say "I dunno, maybe she has a poultice on her sore ear and is saying ouch ouch ouch". Now we have mobile phones, it is "oh my god it must be a phone!"
Same as many UFO reports. In 1000AD it was a celestial event caused by the gods, or the gods were visiting us.
In 1930 after sci fi stuff came in it was flying saucers.
After Roswell and others, now the first thing is "oh my god, aliens!!"