In the presented situation, are you taking the proper traffic lane if you intend to turn left at the nearest intersection?

In the video you are driving on a wide, four-lane roadway in a city, along a retaining wall on the left, towards a flyover; on a gantry over the road there are direction boards, at its sides there are signs F-10 showing the lane layout, and lane direction arrows are painted on the roadway: in the two left lanes, including yours, P-8b arrows to the left, in the two right lanes - straight on. As you intend to turn left at the nearest junction, you are in the correct lane. The answer is: yes.

The Regulation on road signs and signals states that lane direction arrows P-8a "straight on" and P-8b "for turning" mean that from the lane in which they are placed you may only drive in the direction shown by the arrow; a left arrow in the far left lane also allows a U-turn. Since there is a left arrow in your lane, you may turn left from it and you do not have to change lanes; turning left from the right lanes would be prohibited. The Road Traffic Act requires you to signal your intention to turn in good time and clearly, and to exercise particular caution while turning; when two lanes are used for turning, during the manoeuvre you keep to your own path and do not cut in front of the car turning next to you.

Legal basis: § 87 para. 1 and 2 of the Regulation on road signs and signals; Art. 22 para. 1 and 5 of the Road Traffic Act (Prawo o ruchu drogowym)