Just wanted to chime in to say that yeah, the really bad videos are probably due to the foam block not being removed. It is easily missed and didn't exist on the P2. I didn't have any major jello issues on my first flight although I live in a hilly area so it was hard to tell if the horizon was off.
Here's my maiden flight down-sampled from 4k 25 FPS to 1080P.
Edited to add: There's also a sticker on the lens that needs to be removed! I didn't discover that until after that video. It would have made the video better...