It may have been working hard to stabilize the craft and gimbal resulting in jello. I recall there being a max shutter speed cutoff whereby the mechanical shutter reverts to electronic shutter, which I believe is more susceptible to jello.
What I am getting at is that maybe with a slower shutter speed via the use of ND or narrower aperture, if possible, perhaps you could get the shutter speed low enough where the effect would not be present under the same conditions.
As for wimosaur's comment, it tends to be true that for the nicest looking footage a shutter speed 2x the frame rate tends to result in a pleasing outcome, but this is not strictly related to jello or electronic shutter effects, but more of an unnatural seeming effect whereby there is not enough typical blur from frame to frame for movement to appear natural. It tends to look overly digital, or like ultra-crisp movement in a bad way. I don't think that is the case here, though getting the shutter speed low enough where the mechanical shutter is being used might likely help, so it is potentially correct advice but not necessarily for the correct reason.
