Need some help diagnosing noise

This happens so far only when I’m in high gear at idle. The transfer case has a slow leak. I topped it off but the sound is still happening. Occasionally there is enough drag to stall the motor at idle. This has only happened once. This is on a 2012 4 800 (same motor tranny etc setup as an S)

Video with sound is here:

Sent from my iPhone using Tapatalk