It uses vertex paint masks, blue channel is for move amount, green for push amount and red for interval. So through the red it looks like the pieces of the burger are moving independently but it is also important for the other pieces, like the wave movement on the steak. Here is how the burger vertex paint looks like:
Hey all final crosspost from my SCAR-L thread. Haven't worked on it in awhile though it's reached the stage where I needed to call it finished and move onto whatever's next. Few mishaps I'd fix next time around, but better to move forward now than dwell on them