My serpentine belt idler sounded exactly like that about 20 miles before it seized and melted the belt on the freeway. The sound only occurred at certain throttle positions, so I was stumped until it sounded like your vid (before, it may a whistle almost like a turbo). I was actually able to see the run-out in the idler pulley at idle, so I knew it was going out before it seized. On I-5 of course. Luckily the V10 runs without the water pump.
I've also geard a nearly identical sound from an Audi A4 with a bad camshaft bearing.