These skydivers were having fun canopy flocking and the lead jumper got pretty close to the jumper below. Close enough that he tapped the center cell of the canopy below with his foot, which caused the trailing canopy to partially collapse! It appears that, as this jumper (maybe?) released his toggles to go for his cutaway handle, the canopy reinflated and he was able to recover control.
Initially, we thought that this was a turbulence issue. Anything traveling through the air creates a pocket of turbulence behind it. When we're jumping and falling straight down vertically, we call that the "burble." When a wing — be it a plane or a canopy — is traveling through the air horizontally, it does the same exact thing and the phenomenon is called "wake turbulence." That wake spreads out behind a wing and causes turbulence.
However, Richo Butts — an extremely experienced competitive canopy pilot and XRW organizer — reviewed the video and pointed out two things. First, he discounted our turbulence theory and said that he's happy flying his "entire center cell in the burble of a canopy pilot's body in front of (him.)" Second, he stated that at 0:31, it appears that the lead pilot's foot makes contact with the trail canopy's nose. Related to that point, he explained that the stability inherent in a skydiving canopy "is achieved by having the line attachment points farther in from the nose and that's no good when someone stands on it."
This incident could have been avoided had the lead canopy been a bit more careful in his approach. We don't know the experience level of these pilots but coming in like that and making contact is potentially dangerous. Fortunately, it didn't have any consequences more serious than maybe a soiled pair of underwear!
Notably, in this video it appears that the jumpers were (probably) still high enough where a full canopy collapse could have still been dealt with by cutting away. It's important that jumps where canopies are in close proximity are completed, and jumpers separate from one another, prior to descending to altitudes where cutting away would no longer be a safe or realistic option.