Sounds horrible. could it be bad ignition components? when did you replace the wires, plugs, rotor etc.? Also, the startup sounds creepy as well. Which would make me think of the ignition as well.

Try removing the serpentine belt and seeing of the noise stops. It does not sound good, but could just be a bad accessory

Look at how the engine vibrates when it makes the noise. Is that knocking/misfire? Burned valve? It doesn't sound like piston slap. Could be a weird sounding rod knock. The serpentine belt is long and it takes several rotations of the engine for it to hit the same point in the belt. Does the noise g...

That sounds like crossfire to me. Cap, rotor, wires and plugs to get you to where it can be diagnosed. You may find that it went away when you do a tune up.