This is all nonsense, sorry...
The "subliminal" demon flash is seen when Dimmy's mum walks down into the subway in the dream sequence. It was never cut in the original release, or the subsequent Warner Home Video release in the early 80's (before the UK govt got hold of it and banned it)
Some places insistes on trimming those frames out but it was never a wholesale decision. Anyway, it's not subliminal, because you can see them... its a clear four frames... subliminal is one or two frames.
The "version you've never seen", which is one seen usually now, is the one with an EXTRA "subliminal image, longer scenes, the spiderwalk and the new ending.