Its not torque - the plane rolled to the right, torque produces a roll to the left. When you hover a plane, you have to add a bit of right aileron to counter the torque produced by the engine/prop. Everything seems to point to a stall. Remember an airfoil will stall at any airspeed and attitude as long as the critical angle of attack is reached, and one wing usually stalls before the other. Just a matter of too much up elevator with too little airspeed.

Hogflyer