Thought this would be a fun video for OT.
What do you think accounts for the sounds in the video (starting at the 12 min mark)? Video editing/hoax, natural phenomena or...?
Some background on the channel: the guy has been making Youtube videos of abandoned mine exploration for the past several years, 99.9% of his videos are your usual abandoned mine vids. Most of them err on the side of boring. He has one other video with some questionable or "creepy" content (swinging chain in an abandoned mine, voices and an air horn). He also doesn't do very many sponsored/promotional vids (like this one is) and most of his videos have a rather low view count.
Personally I'd like to think there is a natural explanation rather than someone trying to make a quick buck with audio editing equipment, but the sponsored video + visiting a creepy abandoned mine on a dark and stormy night + creepy voices makes it seem like too much of a setup.