Crab, he did not push forward, he was pulled by the line.
Agreed but he was moving very slowly and the aircraft almost pivots in space - is that enough to push oil around in such a manner as to get it to the exhaust? I don't know.
He then keeps the nose down to gain airspeed before pulling out hard which is where the smoke appears - co-incidentally or not with the inflation of the floats.
We are still speculating about the cause simply from the video which may or may not be definitive.