It's hard to describe the sound so it will be easier if you give it a listen. Note that in that video I thought the problem was the brakes but now I think it might be something to do with the transmission since it happens at a stop, but goes away if I shift into neutral.
I just changed the filter and put in 5 quarts of new fluid. It's got the right amount of fluid in it, not too much and not too little.
The sound is not as bad if I accelerate slowly. If I press hard on the accelerator or start on an incline the sound is pretty bad.
The truck is running a little rough and will stall if you leave it sit but I think that's because it has old gas in it. It runs like a normal car on the freeway.