[Vermont Lt]

They hit an ammo dump. Thermobaric bombs are detonated at altitude and the downward pressure causes the destruction.

This video is not that.

[Robert DeLong]

From what I am reading they involve 2 explosions. The first explosion releases gas clouds, and then a second explosion occurs which ignites the gases, as seen in this video (advance video until the the 7:52 mark):

Testing Fuel-Air Explosives / Thermobaric Bomb |

So, if I am correct it would have to explode pretty close to the ground to disperse the gases over a considerable amount of area to do significant damage. But I know not how they truly work, just for doing a quick research.

[Beowulf9]

Oh.