That is a real quiet video. It sounds to me kinda like something on the belt chirping. But then I don't think I've heard a rod knock.
I think I'd slip the belt off and run it for 30 seconds or so and see if the sound goes away. If it doesn't, then that is bad ju-ju, but probably covered. If it does go away, it's probably not that bad - but may not be covered by power train warranty.