Here's the video. I suspect that the bearings in a pulley are dying, but wanted opinions:
It's clearly coming from the rear of the engine (belt area). Sometimes the noise occurs, sometimes not at all. It starts and stops abruptly. Yesterday it was making an even stranger noise, almost like a power steering pump buzzing. Yesterday's noise came suddenly and disappeared suddenly just like today's chirping/rattling noise.
To cloud the matter a bit, I think my PS pump inherently makes a little bit of noise, but I suspect this is due to a PO fluid snafu that I need to fix. But I've never heard a PS pump noise abruptly occur then stop at random.
edit: 82k miles