Need help identifying noise (video)

Gets louder when some throttle is pushed down. Also happens when idle rolling and in park like in the video.

I keep making dealer appointments but the noise never shows up when I want it to. They cant identify a problem they cant hear. Any ideas?

 

the video is small, but there looks like something bouncing around at the bottom right corner/ center of the video that is keeping time with the squeaking.

sorry, I am not a mechanic...

 

Not sure why the video is small But in the bottom right theres just some tape floating in the wind.

EDIT: Video seems to work better on mobile and allows a full screen option.

 

Bumping so this doesn't get lost so quickly. Looking for some input.

 

Dirt in the belt. If you inspect it closely I bet there's tiny rocks built up in the grooves.

A simple, but stupid way to clean the belt is to run a cheap wire BBQ brush along the belt while its running.

Replacing the belt will fix it, but if its not cracked a clean will fix it.

Spraying belt dressing or oil on the belt will be only a bandaid.

It could be a bearing or pulley, but this is just my experience with that specific noise.

 

Will take a look when I get home tonight. What would explain it only happening every so often though? It's like 25% of the time I turn the truck on the noise comes up. Sometimes I drive 2 hours all day and it doesn't make a peep.