Belt tensioner bad?

Thanks for the video. with the noise it is making it sounds like the belt tensioner is bad, but I would inspect the accessory pulleys once the belt has been removed and look for damage or oil which can make the belt slip and then grab. You might want to spray wd40 onto the belt when the engine is running to see if the noise and vibration stops, this will help tell if the belt is causing some of the problems. here are the instructions in the images below to help you with the repair:

1. Using a 1/2 inch breaker bar with a 5/8 inch socket placed on tensioner pulley, rotate tensioner to release belt tension, then remove belt.
2. Route belt over all pulleys except belt tensioner. Refer to Fig. 22, for correct serpentine drive routing.
3. Rotate tensioner to released position and slide belt over tensioner pulley.
4. Ensure belt has correct groove tracking around each pulley.

Check out the images (below). Please let us know how it goes.

Definitely the belt tensioner, absolutely no pressure or whatever when I move and let go, it doesn't move back to tighten up and the spring doesn't recoil of that makes sense. No oil or any liquid from anything else and everything spins when I spin pulleys by hand, no noise from accessories. Belt also is fine, no cracks or signs of wear. Now when I buy the belt tensioner do I need just the bottom pulley or the whole thing.

Update... I have removed the belt tensioner and I believe a spring shot out of the bottom pulley. I can't find where it shot to but I found a washer that musy have been holding it in. The top pulley has a piece missing on the casing

Yep, I would replace the entire tensioner, here it is on Amazon for $34.00.

https://amzn.to/46WnWun

AC Delco Unit. This should fix the problem.