I don't believe that the 4WD models have a wheel bearing on the front as traditional 2WD (with RWD) vehicles would have. You have the CV half-shafts in order to accommodate the IFS. If it was something where one of the boots was torn, you'd certainly see a bunch of grease schmoo flung everywhere. From the video and how everything is situated, I'm going to guess that we're looking at the LF (driver's side). That's also where the front drive shaft is located. Have you looked at the U-Joints? Mine started to squeak/chirp when they were going bad, then I noticed a rougher ride, then when it got real bad, the damn thing shook like it was about to come apart at freeway speed.

When you took the brakes apart, did you see anything foreign embedded in the pads? How about the two pins that the pads slide on, are those smooth and not binding up one of the pads?

I'd imagine that if the seals were dry that you'd have long smoked the shit out of them after 1,000 miles; either that or "yay for Toyota durability". The thing that I'm also considering is that it only happens at under 5-10 mph. I think that at freeway speeds, dry seals would be howling like an animal being skinned alive.

Does it make any noise if you engage either 4-Hi or 4-Lo? I'm far from any mechanic or Toyota specialist, but I'm brainstorming a few possibilities.