You took the words right outta my mouth.... and this is not the Meatloaf song so that ends there.
It was indeed venting liquid oxygen, which is normal when a cryogenically fueled rocket is having it's tanks filled and for a period thereafter.
No smoke.
Though it looks to me (and I by no means have the necessary data to state this as fact) that the ignition point was close to or at the vent, igniting the oxygen and backwashing into the tank taking out the rocket. Short in a fuel hose sensor maybe? Best let the experts decide.