I fly a not that dissimilar aircraft and have now watched the video quite a few times. It is all speculation and I want to pick up my pension - not be a dead test pilot, but;
At low airspeeds my Zodiac with a 912ULS needs half a boot full of rudder. If you add lot of power just before the stall it will either - fly, climb or depart violently to the left. The airframe is vibrating loudly, the nose skyhigh but it can and does depart, once you get into the buffet.
Watching the video they lift off with the airspeed somewhere pretty low. With high power my aircraft will fly, but yaw control is difficult. Given the pretty laissez faire approach in the cockpit I suspect the turn toward the trees was at least partially involuntary.
Whilst the aircraft is then flying, it does not accelerate or seem to climb. So very high angle of attack, high drag and the options are either put it on the ground immediately or find space. Instead there is a 'combined' flying attempt where the nose stays high and headed toward the trees.
The instructor reduces power and the aircraft responds by banking right, away from the trees - but although not obvious from the video I suspect a loss in height was immediately apparent - reflex action - put the power back on?
From then on things were inevitable - no more options and a final pull up.
Certainly my aircraft gives a feeling that little can go wrong, it has a terrific power to weight ratio which allows high levels of pitch and still gives the ability to climb and/or accelerate. At the stall with high power it is much more difficult, as the margin between departing and flying seems quite hard to judge (great power to weight and powerful controls) - allowing that you have top put yourself into a pretty extreme attitude to start with!
So to some extent this video is an illustration of the slightly unusual situations an LSA can get you into. Oh and not really fly the aeroplane.