Are you obliged to stop in front of this level crossing even when you are sure that no train is approaching?

In the video you are driving along a country road and approaching a level crossing without barriers, in front of which there are signs B-20 STOP and G-3 "St Andrew's cross". You are obliged to stop before the crossing even when you are sure that no train is coming. The answer is: yes.

The Regulation on road signs and signals states that sign B-20 means no entry without stopping and an obligation to give way, and that these rules apply accordingly to sign B-20 placed before tracks used by rail vehicles; sign G-3 marks the place where you stop because of train traffic at a level crossing without barriers. The Road Traffic Act requires you to obey the signs and, before driving onto the tracks, to make sure that no rail vehicle is approaching. The obligation to stop is unconditional, because a train is quiet, fast and hard to judge from a distance - you stop before the cross, look and listen in both directions, and only then do you move off.

Legal basis: § 21 para. 1 and 4 and § 78 para. 5 of the Regulation on road signs and signals; Art. 5 para. 1 and Art. 28 para. 1 of the Road Traffic Act (Prawo o ruchu drogowym)