I posted earlier today about my upcoming engine pull. In recent weeks, I've been hearing that same whine, and it was enough to get me off my butt to start thinking about fixing my HG, While it's only leaking oil onto my exhaust and BEFORE it leaks coolant into my crankcase.
At first, I thought the whine was alternator, but I when I removed the belt, the whine continued. I did not remove the A/C belt because I didn't want to deal with the tensioner adjustment bolt that's too deep in the bracket for a box wrench, and the space 'tween the fan and tensioner bolt that's too small for a socket.
After reading the post, downbounds reply, (and listening---Brilliant!) to the video, I decided to pull the A/C belt. (I shortened a spare 1/4" drive 12mm socket by about 1/4" , in a vice with a cut-off wheel on a hand grinder and used a 1/4" drive flex-handle. There, that's better!)
The loud, action-inducing whine that was similar to the OP's was gone. I pulled the idler and bracket. The bearing was definitely shot. I'll either replace the whole pulley or maybe just the bearing.
There's still a slight whine that could be attributable to the timing pulleys, so I'm still aiming for the engine removal. I shouldn't procrastinate. I shouldn't.