AHH! there is two o-rings! i thought so. So i changed out the one thats right in the middle/bottom of the pump, the one you can see in the video clearly. I didn't touch,change the one thats on the very top top(The line runs across the entire engine that line), i had no idea that top one had an O-ring. The only one anyone mentions is the on thats on the middlish/bottom that has a hose connecting to the reservoir. Ill try and find that P/N for the top O-ring tonight and order it since they are always cheap.That first youtube link doesn't work, the second one did.
My best bet would be the power steering pump. Mine started making a similar noise now that the winter months hit. All I did was change out the O-rings for the power steering pump. I bought the set of o-rings, a new PS reservoir cap, and 2 bottles of PS fluid for 20 bucks. Over time the o-rings wear out and don't seal as well as they used to.
The sound would increase with higher RPMs and would still be present at idle. For me it was only the o-rings that needed replacement, it might be the same for you. It's a good place to start, and relatively inexpensive. I think the 2 o-rings alone run like 10 bucks if anything.
I would say it could also be the alternator whining, but we would need more information for that. Are you having any other issues? Any lights dimming or things of that nature?
but I DID do the middlish/bottom one.