In this situation, should you signal the overtaking manoeuvre with the appropriate turn signal?

In the video you are driving in the right lane of a dual carriageway; in front of you, near the right edge of the lane, there is a motorcyclist whom you intend to overtake, and the left lane is free. You must signal the overtaking manoeuvre with the appropriate indicator. The answer is: yes.

The Road Traffic Act requires a driver to signal an intention to change direction or change lanes with the indicator in good time and clearly, and to stop signalling immediately after completing the manoeuvre. Overtaking on a roadway with marked lanes means two lane changes: into the left lane before you reach the motorcyclist and back into the right lane after you pass them, so you signal them with the left indicator and then with the right one. Before the manoeuvre you make sure that you have sufficient visibility and space, that nobody behind has started overtaking you, and that the motorcyclist has not signalled an intention to change lanes or direction. When you overtake a motorcycle, the Act requires a lateral clearance of at least 1 m, but on a two-lane road it is safest to overtake using the whole left lane: a motorcycle is sensitive to the blast of air from a large vehicle and to bumps in the road, so it may suddenly swerve to the side. You return to the right lane only when you can see the motorcyclist in your interior mirror.

Legal basis: Art. 22 para. 5 and Art. 24 para. 1 and 2 of the Road Traffic Act (Prawo o ruchu drogowym)