This is an example of a high round out that Paul Voight mentioned, with trouble
getting good body/hand position that allows for a good flare. The pilot slows to
near trim speed high (gradient or wind lull might not have helped either), gets
hands up, but never achieves a good upright position that allows high enough
hand placement for a strong flare. A bit of pitch bobbling bleeds off even more
energy and a late flare from a weak position results in a belly landing.
Here the same pilot gets better body/hand position and flares earlier with good
result, but still doesn't really bleed of his speed low enough and in ground
effect. Although hands are still a bit low and the body not fully upright
(prevents getting the keel vertical in the flare) the timing and flare
strength/quickness is enough to get a decent stall of the glider and a nice
landing.