There may be some effect caused by descending/putting
the lower wing down through any wind gradient but this
actually improves the situation as the air is moving
'away' from the path of the glider more slowly and
will consequently cause some increase in airspeed.
(You can try the opposite of that effect by pulling
up from a downwind racing finish through a strong wind
gradient; watch the airspeed decay at an alarming rate).

The biggest problem is that the apparent speed over
the ground in say a 15kt wind jumps by 30kts and results
in people trying to reduce the ground rush by raising
the nose with no reference to the ASI.

There is also the potential of poor turn coordination caused by the
perceptual changes that occur when maneuvering below pivotal altitude,
although that didn't appear to be the case in the video. The
suddenness of the departure was a bit surprising, but it seemed to be
triggered by the opening of the spoilers rather than by any obvious
lack of coordination.

- Rich Carr