Clearly the wind is swirling due to the proximity to the treeline, which would not be unexpected.
But the lifting off is more due to finger pinch or the angle of the finger beneath the shaft applying pressure to the underside of the shaft.
This is particularly noticeable in the two shots by the bloke in the blue shirt where the finger pressure lifts the shaft off his hand as he comes to his length.
Consider the angle of his fingers as compared to the shaft and the tightness of his grip.
The young chap at the far end of the line has a similar but more obvious version of the same problem with his first attempt at a draw.
It's definitely a technique issue, no doubt at all.
This is a very common fault and is easily enough cured, though it will be aggravated by a loose nock fit or by tensing of the hand with a higher draw weight or by trying to hold the shaft too firmly.
But it is basically a question of good finger alignment through the draw, so as to not apply exessive pressure to the underside of the shaft, or to reduce excessive pinching which will have a similar effect, though it is easily enough distinguishable from the former cause with a little care and attention.
But first I would look to check and optimise the nock fit so that a literal pinch was not dictated by a loose nock fit, then I would look to the alignment of the fingers (and forearm) through the draw.
A day teaching the fundamentals never goes by without folks asking why the shaft falls off their hand as they draw.
And they are always told the same thing.
The shaft rarely falls off your hand outside of extreme wind conditions, it is almost always a product of the shaft being pushed up by excessive pressure of the finger against the underside of the shaft.
Less commonly by gripping the shaft between your knuckles and waving it about.
In this case, the former is the main culprit here.
Rod.
