You are driving a vehicle in the built-up area. In the presented situation, are you obliged to allow the bus driver to join the traffic?

Yes. According to Art. 18 para. 1 of the Road Traffic Act, a driver in a built-up area is obliged to allow a bus to join the traffic. The video shows that the bus is indicating its intention to pull out from the bus bay with its indicator, therefore you should reduce your speed and, if necessary, stop to allow it to do so.