Hmm, I just watched the video.. It doesn't sound oil related. you can hear that clack-clack-clack and a slight tk-tk-tk-tk-tk that is the engine rpm it is uniform together.. But this whine, I think it is pump related.
You can hear it kind of still remain after the engine has dropped to idle? That is the way the pumps works it spins down after the engine hits idle, because of the flyweights inside of it. Physically the pulley is still spinning the same speed, but the weights and governor are still working to bring the idle to a solid, and not let it hunt around for an idle. Like a lope.