Are you allowed in this situation to enter the level crossing, if the red light has already gone out, but halfbarriers are yet the be fully raised?

The video shows that the half-barriers are only just in the process of being raised and are not yet fully open. According to Art. 28 para. 3 pt. 1 of the Road Traffic Act, the driver is prohibited from entering the crossing if the lifting of the barriers is not complete. The fact that the red light has gone out does not exempt you from the obligation to wait for the barriers to open fully.