In this situation, when changing to the left lane, are you obliged to give the right of way to the vehicle in that lane?

In the video you are driving in the right lane of a road along a green area; ahead of you the lane ends - a sign by the road and lane-change arrows P-9 show that you must move into the left lane, where other cars are moving. When changing to the left lane, you are obliged to give way to the vehicles moving in that lane. The answer is: yes.

The Road Traffic Act states that a driver changing lanes is obliged to give way to a vehicle moving in the lane they intend to enter and to a vehicle entering that lane from the right; the exception is the zipper merge (jazda na suwak) when speed is significantly reduced. The Regulation on road signs and signals states that lane-change arrow P-9 means an obligation to move into the adjacent lane. An obligation to change lanes does not give you right of way - you switch on the indicator, match your speed to the traffic in the left lane and move into a gap that will not force anyone to brake.

Legal basis: Art. 22 para. 4 and 4a of the Road Traffic Act (Prawo o ruchu drogowym); § 87 para. 3 of the Regulation on road signs and signals