This is ACC Innovation's quadcopter model ThunderWasp GT using a standard bambi-bucket used for aerial firefighting. It carries roughly 270-300 litres of water and weighs around 340 kg fully loaded with water and the sling carrying it.
The reason the bambi-bucket is not getting filled directly a few times in the video is because the pilot forgot to flip back the switch controlling the release mechanism of bambi-bucket.
The video is minimally cut to show case that the ThunderWasp GT is capable of continuous firefighting with the bambi-bucket. There is no need to land for battery recharge or refuelling. The ThunderWasp GT can do this kind of fire fighting continuously for about 1,5-2 hours, without the need of refuelling. Once refuelling is needed, the refuelling process is a matter of minutes before it is ready again.
Imagine the potential of firefighting a swarm of this kind of drones would have. Continuous firefighting without the risk of human life, making it possible to put out fires in almost any weather and smoke condition, day and night.
