If it wasn't for the fact that I can speak from some experience, I'd not comment given that I find this a really trivial matter given that someone else on this board (Linda) just had a close friend die.
Ok folks! That bit on youtube "played backwards" doesn't sound like recorded sound played backwards at all. When I was in high school, we had a "language lab" in which we had these cassette players with tapes that wouldgive you a foreign phrase (I took Russian), and would then record you saying it and play it back to you, so you could carefully check your pronounciation, accent, etc. The way these tapes and the machines they were played in worked was that the instructional tapes would be recorded on one side and it could record on the other simultaneously. It was able to do this by recording on the other side backward, and then playing it back to you backwards, so that it sounded forwards.
Realizing this was how it work I experimented. I had a cassette of the Love Stinks album by the J. Geils Band. Y'all know the "song" (more like just a story) "No Anchovies Please"? remember the part where it says "Upon awakening she finds herself in a strange foreign speaking nation, and then you hear what sounds like someone saying something way too fast. That's backward speech! if you play it backwards (which I could do at normal speed), it says "It doesn't take a genius to tell the difference between chicken shit and chicken salad." And it's VERY VERY CLEAR. No mistaking it for anything else. The backwards recording your hear there doesn't sound anyhting like the supposed backwards play of Stairway to Heaven. Having this experience, I can say with great confidence, that the so called backwards playing of it in the clip, is really something else entirely!
But since, I want this to be a bit more meaningful, I'll add this.
Acujer, you seem to have an obsession as it were with this subject. I wonder why. You seem the post often on this particular subject. I personally don;t think there is such a thing as Satan. At least, not as a corporeal being or a uniquely conscious entity. If however, you define "satanic" as "evil", there sure as hell (pun intended) is plenty of it in the world, and with war, corporate greed, the slaughter of innocents by the thousand, rape, child abuse, etc; I find these things far worse and far more evil than anyhting done by people in adolescent rebellion (even the older folks still stuck in that phase) who like to do shit like turn pentacles upsidedown and chant "Hail Satan!" If you want to do something about the evil you see in the world, I think feeding someone who is hungry is far more good than "exposing Satanism" in music. This is a friendly board, and I don't have any problem with you expressing yourself on it, heck, I'm glad you're here. And I in my own expression, say that I'm concerned why you seem so facinated with this subject and go back to it so often, though I acknowledge that the majority of your posting are not on this subject. If indeed you find the subject of evil worth studying so future evil may be curtailed and you want a book that's scholarly and something other than fundamentalist Christian paranoia, I recommend People of the Lie by M. Scott Peck. Check it out!