Engine noise - 2000 Protege LX 1.6l

I've got a noise coming from the drive belt area that I would describe as sort of a hollow, metallic gurgle. It increases when throttle is applied, but you can still hear it while idling when the hood is open. It's mostly noticeable at lower speeds, although this could be due to ambient high-speed noise drowning it out.

Anyone know what this could be? My guess based on the location is maybe a pulley or bearings. No CEL illuminated.

Video: the sound doesn't come through great on my phone, but it's you can definitely still make it out.

I vote waterpump

I was afraid of that.