What is this unusual leading edge flap on a B737-200? On this video of Air North's gravel runway-equipped B737-200, there's what appears to be a small leading-edge flap (Krueger flap?) inboard of the engine.  Refer to the screen shot below.  What is this?



Addendum

Notice in the video (and screen shot) that this device shows itself while no other flaps are extended.
These are two leading edge Krueger flap surfaces at each side of the wing, you can see details about them according IPC and AMM documents I found over the internet:







Regarding the Addendum, and why it seems that there is no other flaps deployed, I found a similar topic at Airliner.net Forum. As it is mentioned there, when is no hydraulic pressure, they can be extended by their weight:


  ...it has to do with the shut off valves and the actuators relaxing with no hydraulic pressure on them.


and also:


  ...Pressurize the system and they all move to their present commanded position


and another sidenote:


  ...Someone pulled that Krueger Flap to the fully extended position. When they droop because of no pressure on the system there in the mid positions. 


and as final note, this issue is also mentioned in the AMM: