'FIRE TORNADO?' you say? Yes, but although it sounds like something that Ron Burgundy would make up, it's a real (if rare) natural phenomenon.
Fire whirls, also known as fire devils, fire tornadoes and firenadoes, occur when rising heat and flames combine with turbulent wind and start pulling in debris and combustible gases to stoke themselves in a tornado-like fashion and are a pretty terrifying thing.
Armed with that information and their slow motion tech, the Slow Mo Guys decided to make and film their own natural disaster on a small scale. Don't try this at home (but do feel free to marvel at the wonders of the natural world).