As I downshifted from 2 to 1 I heard a little noise and then a very, very loud whining noise started. I goes on for about 20 seconds then stops. It only happens when the cars idling and not moving. I took the risk of driving home after taking this video and as I was driving it felt totally normal and I didn't hear the whine once and neither when I got home. I don't want to shrug it off as something small because that would be stupid. I recently got work done when my serpentine drive belt ripped because the pulley snapped so I had that and the belt replaced about a month ago. Im wondering if that has to do with the whine. Please help me out, thanks.

 

What video?
Best thing to do is, with engine OFF and COLD, remove the belt and inspect each pulley AND each accessory (A/C compressor, P/S pump, and alternator). Everything should be solid and spin freely with no grinding or rumbling. Even if the incident was a one-off I would inspect everything just to ensure all is well under there- especially since work was done on those exact components recently.

 

whoops, i just linked the video. and thank you for the reply. i think i'll take my car where it was worked on so they can diagnose it and go from there.

 

I doubt it is a pulley/ bearing. The usually squeal and grumble.
That sounds more like one of the electric fans. Make sure nothing is hitting the fan blades. Turn the AC on and see if the noise returns.