Final answer:
The footage captured during the August 2019 eruption of the Stromboli volcano in Italy shows a hazard known as a pyroclastic flow, which is a fast-moving current of volcanic gas, ash, and debris. This type of hazard can be seen between 20 seconds to 35 seconds in the video.
Step-by-step explanation:
The footage from the August 2019 eruption of the Stromboli volcano in Italy caught a type of hazard called a pyroclastic flow.
Pyroclastic flows are fast-moving, high-temperature currents of volcanic gas, ash, and debris that flow down the slopes of a volcano.
In the video, between 20 seconds to 35 seconds, you can see the pyroclastic flow moving rapidly down the mountain.