Zero resultant moment in Oxford

This mobile crane was dismantling a tower crane in Oxford. I was watching it remove the concrete counter weight. Notice that the crane has vehicle has extended its legs onto the pavement to increase its base area. The line of action of the concrete weight lies outside the base area, so how come it doesn't topple over? Look at the design of the foot of the extending arm. The motor that drives it overhangs in the opposite direction to the arm. The motor will be heavy. It will exert a moment in the opposite direction to the concrete weight. If the motor is heavier than the concrete load, it can be a smaller distance from the centre and still have the same moment as the concrete load, which is a bigger distance away. Overall the resultant moment will be zero and the crane doesn't topple. The centre of mass of the whole system must be such that the line of action of the gravitational force acting downwards from that point must lie within the base area.