A demon groaning?
That is indeed a strange noise, I don't recognize it. Sometimes it's hard to discern noises from recordings but it sounds like a creaking noise to me. Not much in the drive shaft that I can think of that could make that sort of noise. When you rebuilt the shaft, did you replace the center ball / socket yoke? It kind of looks like there's a new boot on there.
I'd maybe unbolt that end of the drive shaft and see if you can replicate the noise with just the drive shaft or by just rotating the output yoke on the transfer case. Maybe you can isolate where it is coming from that way.