Sorry guys, but I didn't get to the video and didn't comment sooner, but here is my take.
I am really confused how the fire on the Tesla car could be caused by the battery current.
Having been in an electrical fire, I can tell you it did not look like that. Now I will give you that an electrical fire can become a different kind of fire, but you need to have combustible materials igniting. Could the paint have produced those flames?
The arcing of an electrical fire does not produce large flames. It produces current hot spots where the short circuit is complete. Water will not extinguish and electrical fire, and their is extreme heat, but little flame, mostly a bright orange glow at the arcing point, and sparking which gives off white light.
I don't know what else is in the car that could produce a fire, but here is my take on what Tesla should do now.......try to reproduce the event in their lab. If someone can demonstrate that the random scrap metal on the road can get into the engine compartment, lay perfectly and stable so that a constant arc is created, then maybe I'll be a believer. Until then, I think there is a lot more to be investigated here.