Sorry for my late reply.
The small plank pieces seen on the live video stream are used to start the circulation pumps in the liquid resistors. There are two liquid resistors used as variable rotor resistance for the electric motor.
The liquid resistors consist of about 2 m high containers, in which electrodes made from stainless steel are dipped into the liquid consisting of water and sodium carbonate. The liquid level in the containers may be varied by “sluices” controlled from the control board (you can see the operator adjuating the liquid level several times during the startup phase). This regulates the resistance between steel electrodes and thus controlled the rotor resistance. The heat generated is cooled off in the liquor through a heat exchanger for cooling station facility. Read more about this and watch video (Swedish language) here:
Fredrik / AlexnderSAQ