I am not really hearing a pinion bearing sound, and wheel bearings may not be as vocal while the tires are in the air with no load on em. What I do hear sounds to me like carrier bearings. I have fixed a few trucks (nissan) with these problems.
A good rule of thumb:
When pressing the gas or coasting above 30mph you hear a hum similar to MT tires (but you have ruled out tires) it is probably a pinion bearing(s)
When you are at parking lot speeds and you hear what sounds like marbles in a can or gear grinding noises, its probably a carrier bearing(s).
wheel bearings can be checked for side to side play, however if you open up your differential to change bearings of any sort, you should prob. also just swap out your wheel bearings to since you will be pulling your axles shafts anyways.
Thanks for the help. I have all my parts for the wheel bearings, and im about to buy all the bearings for the diff. I just wanted another opinion to be sure i am not tearing into the diff for no reason. I have both low and high speed noises. Nothing sounds like marbles rolling around just yet, a very bad bearing noise, sounds like mudder tires like you said. Thanks, Paul
Yah I can almost promise that if you get a master rebuild kit for your rear end that the issue will go away. Try changing oil first and see if it helps if you haven't, it MIGHT help...
Just please make sure you know what your getting into when you pull the pinion or ring gear. Lots off critical tolerances in there that can rly ruin your day if they are not set properly. You CAN do it, there are plenty of good guides online. It just takes a little know how and is a bit tedious. All this you may already know, just throwing it out there.
I had the pinion bearing go in the M226 in my Frontier. At first, it would only make whining noises when turning slightly to the right, with my foot barely on the gas (like on highway on ramps). Over time the whine got louder and louder, and would do it even when going straight. It all depended on how the rear diff loaded up the bearing.
From the video, it looks like you have a C200. It's tough to say where that noise is coming from though.