In the situation depicted, are you allowed to drive onto the railway crossing?

In the video you are approaching a level crossing with half-barriers; the signal is showing a flashing red light, and the half-barriers are being raised. In this situation you are not allowed to drive onto the crossing. The answer is: no.

The Road Traffic Act prohibits the driver of a vehicle from driving around lowered barriers or half-barriers and from driving onto the crossing if their lowering has started or their raising has not finished. The Regulation on road signs and signals adds that a flashing red signal means no entry beyond the signal. In the video both conditions of the ban are met at the same time: the barrier arms are still rising, and the red light is still flashing. This is the trap that drivers fall into most often - a train has just passed, the barriers are going up, so they move off "because it is allowed now". However, the raising may be stopped when another train is coming from the other side, and the red light goes out only when the system decides that the crossing is safe. So you wait until the half-barriers are vertical and the red lights have gone out, and only then do you move off, still looking both ways along the tracks.

Legal basis: Art. 28 para. 3 point 1 of the Road Traffic Act (Prawo o ruchu drogowym); § 98 para. 5 of the Regulation on road signs and signals