Does anyone know what is causing this noise?

Here is the noise:

https://youtu.be/sy2xgT-lJhU

 

My guess would be the belt tensioner. Could be the alternator. Loosen the tensioner and give it a spin, see if it spins well or if it binds up or sounds like it's got sand in it. It's a relatively cheap part to replace. If it's the alternator, it's a bit more of an expensive thing, but there's a chance it can be serviced. If both of those check out, keep going down the list of spinny things until you find the one that squeaks

 

I replaced both the belts and checked the tensioner which was fine. I'm guessing it possibly could be the compressor/clutch making the noise...