The plane was overloaded for the conditions - the take-off run went on forever and he should have aborted waaay before it eventually dragged itself off the ground.
Then, when he fails to make enough height to clear the trees he attempts the 'turn of death' turning back downwind towards the 'runway'.
As he turns downwind he effectively loses a load of the air over the wings that is keeping him aloft. You never turn back even if the engine fails at take off - you always attempt to dump the plane straight ahead into the wind.
Air pocket - my big, fat, hairy arse.
Just my humble opinion of course....