Dodge T is correct. If you're heading from the Tosside direction up towards Whelpstone Crag on the fire road, this unofficial route is just on your left immediately after the 3rd (and smallest quarry with the steep drop). The Nambs DH route used a slightly different drop in about 6 ft further down the fireroad which was less steep, but turned a corner part way down. It was nice and dry when I took the video, but it can be quite slippery at times and there are often trees down especially after high winds. It's good fun though.
p.s. I wondered why views had suddenly gone up on YT!