The YouTube video is a pretty good microcosm of what happens in big fires. This fire was actually caught by a dust devil, and sprouted into the air during a bushfire. In big fires, the fires themselves create vortexes that produces these moving fire tornadoes.
According to the filmmaker, the fire tornado made a noise like a jet engine. That’s typical of bushfires when they’re moving at speed across country, and some Australian bushfires have hit incredible speeds, something like 120kmh (75mph) or higher.
This area was also very dry, meaning the fire was able to move and pick up fuel as it went. It’s amusing to note one of the comments on YouTube, wondering “how people could live without rain for 6 months”. Some areas in Australia don’t see rain for a decade at a time.
It’s a bit of a pity that the video gets stuck with a title bar for a while, but watch the flames as they rise. That really is a jet of fire, nature’s equivalent of a welding torch, and about as hot.
Fortunately, these roaming fire tornadoes are pretty rare in Australia. Arsonists are quite bad enough without them, too.