Honestly I need to watch it again as I saw it back in January, but essentially it's argued that Alien shares thematic philosophical elements with the Greek Furies of mythology, though I can't remember the specifics of the comparison. Yeah it's weird, the documentary is weirder than Alien fans will be used to but that's what made it unique for me. It's a part of the film, the whole documentary is not hinged upon it, as lots is just about the history of Dan O'Bannon's involvement.