Since it is 4wd, it's likely that turning is placing enough load on it to cause the noise. What I would suggest is to remove the driveshaft and inspect the splines on the yoke and the output shaft at the transfer case.
If the splines are good and there is no evidence of damage, it is likely related to the final drive gear or one of the transfer gears. See pic 1. I highlighted the areas of concern.
Now, when I think about it more, since the video is of the front U-joint (transfer case) and it moves, that would indicate the problem is after that point. Does the same thing happen at the rear differential? I ask because the entire driveshaft is moving. So, the transfer case is causing it to turn approx 90° meaning something after that point has to be doing the same thing. Also, when you make a turn, the rear differential has to accommodate one wheel turning faster than the other. Ugh! I have a headache. LOL
Sorry for jumping around like that. The second thought just popped into my head and I felt it was important to ask.
Let me know.
Joe
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Friday, May 21st, 2021 AT 7:32 PM