First flight today; I was nervous so I left the gimbal cover on and got the footage back and discovered a sort of white hair flickering back and forth.
Any ideas?
Yep...that looks like just a reflection from the sun or props or something. Take it off as there is a fan to help cool all of the electronics within the Mavic that is located behind the gimbal/camera.
I had the same effect with the "fish bowl" when I bought mine. On my first few flights I left the gimbal cover on until I was comfortable and bought a lens cover to protect the lens directly.
At Sixteen seconds in looks like Manny Moe and Jack or Larry, Moe and Curley. Hard to tell.