Hi evryan, what I can see in your video is more like a moire affect where the patterning on the grass causes issues with the sensor. This is quite normal for camera like the Phantoms. Many DSLR's had these issues such as the Canon 5Dmk2 etc.. So I wouldn't think it's something to be worried about on our Phantoms!
I didn't notice any stepping of the aperture though.. Or should I say of the image brightness, as bradbrok quite rightly pointed out the P4 has a fixed aperture.
Having thought about this since my original posting, it's more likely the shutter or a combination of auto EV'ing and shutter as these were (deliberately) left in auto to see how the camera would perform. I would advise set to manual and take a note of your camera settings see what works for your environmental conditions.
However, if you want reliable decent images I would NEVER recommend using auto anything. Some people like to use auto white balance but even with this, if you move the camera the lighting will change inevitably so set camera settings to MANUAL before commencing any shooting:
Take the camera up, start off in auto if you wish to get ballpark settings, switch to manual and adjust accordingly.. Then Press Record!