Interesting! Thanks for the feedback! It certainly is worth checking out. Thanks for the links and videos as well.
Some of my shots at full zoom on a tripod were rock solid, so I guess it’s just a random issue that could be avoided by turning IS on all locked off shots?
Another interesting note. There was a clip I didn’t include in the Vimeo link where I had the same jello effect (not nearly as bad though) with a handheld shot at full zoom, but I was looking through the EVF. The EVF on the GH4 is a real blessing as it provides another point of contact and stabilization when a tripod isn’t available. The image itself had almost no shake, though it was a little jello-y. I guess a testament to the IS of the lens and the usefulness of the EVF!