In this situation, are you required to signal your intention to return to the right lane with the direction-indicator?

In the video you are driving along a residential street among houses; on the left a white van and a silver minivan are parked, and at the right-hand edge of the roadway there is a dark passenger car, which you go around by moving onto the left side of the roadway; after passing it, you intend to return to the right side. You are obliged to signal your intention to return to the right lane with the indicator. The answer is: yes.

The Road Traffic Act requires a driver to signal an intention to change direction or lane in good time and clearly with the indicator, and to stop signalling immediately after completing the manoeuvre. Returning to your own lane is a change of lane just as much as leaving it, and the signal matters to a driver who may come from the opposite direction and sees that you are about to get out of their way, and to drivers behind you, who may want to go around the parked car after you. You switch on the right indicator, check that you will clear the dark car with enough distance, return smoothly to the right side and switch off the indicator.

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