Sunny, the camera would have to be massive to be any problem. NOO used to have single controls ( Pedals were inserted and held with a wingnut) and the column coming from the floor in the centre over in front of the pilot. It has a throw over switch to move the yoke over to the other seat.
Miss-handled flap action and being in the centre of the valley with not enough room for a fully loaded slow turn inside the valley peaks, would be my (Beaver experience) guess.
The flap action has been mentioned before but discounted because the flaps were found at the take off or climb position. NOO when it was used on AG work had the modified setup that always had down selected. I haven't seen a float equiped Beaver with it fitted. It used a motorcycle brake lever to pull the flap position to up before pumping hyd. main lever. A heavily loaded Beaver sometimes needs more than takeoff or climb flap, depending on the situation. With Flap down and flying slowly, a quick couple of pumps moving the flaps up would stall the aircraft. If the flap control lever was still in the up position this could have happened easily.
This has previously happened to AG machines, usually taking off. In the early days of Beaver AG ops it happened a few times, It was directed then flaps should be set at take off before roll started. Standard practice was to have flaps set with just a couple of pumps then as flying speed reached a couple of pumps had the aircraft flying. As mentioned before aircraft were modified in both NZ and Oz.
With no obvious cause my theory would be not enough room for a slow heavily loaded turn inside the valley, trying to tighten the turn radius by pumping flaps down, they went up instead of down (due flap movement lever in the wrong position) and stalled.