Hovering white light....damage to metal structures....some form of ball lightning?? I'd check the the crystal structure of the metal where the blade broke off under a SEM to see whether it's been recrystallised. You can tell the difference between recrystallisation caused by metal fatigue and that caused by a sudden input of energy.
Something just crossed my mind....it wasn't a "what" but a "who". Notice they had an advert for "Top Gear" on before the article on You Tube??. I know what caused it all. It was the boys doing some stupid stunt and it went wrong on them. Either that, or The Stig missed a corner and went airbourne
