wheel bearings
 

I am getting a rhythmic sound on the highway. I thought it might be a wheel bearing so heat gunned the hubs after highway and both were 168 degrees. So I'm thinking that's not it, especially since Blaze only has 80,000 miles. The tires are pretty new. Brakes don't squeak but IDK how old they are.
I did notice an intermittent rattle sound yesterday in the engine area, sounds a little like a off balance hamster wheel. I thought it was something loose on the trailer in front of me but it was me.

Should I be concerned?

A quick check is to raise the front tires and check for any wobble or looseness in the hubs. You should not feel any looseness.

Have you tried this?

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Agreed. A bad wheel bearing will not always heat up more than normal. They'll start making noise and you might start feeling them while driving before they begin to produce excess heat.

Usually the "wobble test" will tell you what's what. If still in doubt, pull the brake caliper and pads off to rule them out and spin the hub over by hand. If you can hear or feel a grinding or "notchy" rotation, then you can almost bet it's the bearing. I've had them be bad, only being able to feel and hear them from in the cab, but the wheel didn't seem any more "wobbly" when lifted up. Pulled the wheel off like I mentioned above, and I could feel the grinding when rotating it by hand.

Car passed the wobble test on the driver side. While I was there I checked the outer brake pad and it had 1/4" remaining.
Maybe I was imagining it.

Always be concerned about noises, they are telling you "Im about to break and leave you walking"

Very often its a bad road surface. Semi trucks do bad things to asphalt.

Drive flat road, even throttle, then just barely accel and decel, that will show driveline problems like a U joint or differential.

Steady speed, driving straight, turn ignition off but DONT lock the steering column. Listen for noises. If the steering column locks there may be other noises like hitting a tree!

The wheel bearings are very low mass and coupled to both the spindle and hub, a bad bearing may not show up in a heat check on the hub (unless its about to turn red hot) especially with drag on the brakes.
To isolate the brakes, use a C clamp or screwdriver to push the piston-side pad back so the pads dont rub and drive it. Of course that means cant touch the brakes as that will reset the pads. Make sure to not run into a tree (bad noise).

Jack up each wheel. Put a brick or other object near the tire tread face (tread pattern), point the corner of the brick at the tread pattern and rotate the wheel by hand- look at the tread pattern against the brick- does the pattern move side to side? If so, the tire is defective.

The rotor has some movement behind the lug locking nut as seen here
https://photos.app.goo.gl/AWfa3YK9AXznt2UW8

The video just shows that the retaining clips are not holding the rotor to the hub. I can see a gap opening an closing when you move it.

The better test is to reinstall three of the lug nuts on to the studs to hold the rotor in place. Put them on the studs without the clips. Then with the nuts installed, try your test again. By doing this, you will have more leverage at the edge of the rotor to cause any movement and being a larger radius than the hub itself, you'll have an easier time detecting motion.

And FYI, I've never seen rotor retention clips before. Are these the original rotors?? It is amazing that they had not been discarded after all these years.

And do you suspect the rear or front bearings?

Note that in my reply above I did a bit of a brain-fart and answered as if your video was of a front hub on a 4wd model.

If the rear bearings are bad, then I would think you might feel some free-play for up-down/forward-back motion not so much in-out.

The clips are probably original, the truck only has 70 or 80K miles. It's a RWD.

The noise is Wooh, wooh like the wheel is loose on the lugs or tire is out of round. Treadwear appears even, 6 months after I replaced the control arms and a DIY string alignment. The pads have 1/4" still on them, maybe they are original too, IDK. Tires are pretty new, knobby style, maybe they always make that sound?

Tire noise is a thing depending on the type of tread. But any noise from treads will be constant at constant speeds.

You say the tires are new. How old are they? I just want to make sure we are not talking about new-looking tires as tires can age, even those that look good.

I'd suggest also doing a proper check of the rear axle. All I know about this is that the differential gears can make some odd noises; moaning etc. Have you checked the gear oil in the rear differential? You might want to change it just because it is likely due for it.

But more importantly, I'd suggest you get an alignment in a proper front-end shop. This will make sure that everything is where it should be.

Finally, have you checked the rear axle bearings?