In this situation, when turning left, do you have to yield the right of way to oncoming vehicles going straight on?

According to Art. 25 para. 1 of the Road Traffic Act, a driver turning left must give way to vehicles approaching from the opposite direction that are proceeding straight ahead or turning right. The green signal shown in the video (general traffic light S-1) permits you to enter the area beyond the signal, but it does not exempt you from the duty to give way. When performing this manoeuvre, you must let all oncoming vehicles pass.