What is Reddit's opinion of Ghosts Caught On Film: Photographs of the Paranormal?

From 3.5 billion Reddit comments

Would love to see a proper citation for that, and not one from a self-published "psychical researcher" whose most lauded qualification is "council membership of the Ghost Club" [link], much less one who suspects a link between English folksong and pre-Christian paganism, an idea widely discredited by academics.

I can find a lot of vague assertions online that the song is traditional (some of which tie it to Cecil Sharp's scholarly activity; this is nonsensical, as neither the poetry nor tune are anything he would have been cared to collect, much less publish) from folks clearly not in the know. Allan Brown's Inside the Wicker Man, which appears to be at least slightly reputable on the subject of the film (and is probably the source for Melvin's claim up-thread), writes that Giovanni "manufactured" the song [link] from an older piece, but is again short on details. From my own expertise, I can state that the tune is modern (turn-of-the-century music hall at earliest), and so is the poetry. I can't find a trace of it in the Ralph Vaughn Williams online collection, or in the Santa Barbara English Broadside Ballad Archive, or in the Bodleian's digital broadside collection, or in the Jack Horntip collection of bawdy songs or in any of the older texts it hosts. If it's truly a "reworking" of an eighteenth century song, it's mutilated past recognition.