Whoa. It looks to me like the wind itself is flammable. It might be some kind of outgassing phenomenon coupled with strong winds. Propane and Butane, for example, are heavier than air and could conceivably cause that sort of slithering fire as they would get pushed by the wind along the ground, but then again, they would have to be huge concentrations for it to not vaporize in the open air. Maybe a gas leak?
Just speculating, but that was my first impression.
It does look nuts, though.
Cleveland fire investigators say it was actually a small fire that started in a mulch bed, and strong winds caused the flames and embers to then spread to other mulch beds. The story began to unfold just after 2 a.m., when customers and employees leaving bars and restaurants on the East Bank, reported that no less than 20 mulch beds were on fire.