Are you allowed in this situation to stay on the left lane, when there are no vehicles driving on the right lane?

In the video you are driving on a dual carriageway in the left lane, although the right lane in front of you is free - the cars in it are far away. Since you are not overtaking anyone, you must not stay in the left lane: you go back to the right one. The answer is: no.

The Road Traffic Act requires you to drive as close as possible to the right edge of the roadway and, on a roadway with marked lanes, to occupy only one of them. The left lane is for overtaking, and after the manoeuvre you must leave it. A driver who "occupies" the left lane forces others to overtake on the right or to drive close behind that driver, which is particularly dangerous on a fast road. You check the mirror, switch on the right indicator and move into the right lane.

Legal basis: Art. 16 para. 4 of the Road Traffic Act (Prawo o ruchu drogowym)