I heard this noise the first time 4 days ago and hasn't came back until today. When accelerating the noise stops after 1500rpm but then returns once accelerating again. Once the car is 100% warm the noise goes away after 5 mins or so. Car is stock other than lid/exhaust/free mods. Please help!

First video is accelerating.
Second video is from under the hood then underneath the drivers door.

 

My guess is exhaust manifold leak since it goes away when warm.