That fun fact may be true, but ask any firefighter that has had to put out a lithium based car fire how fun that fact is. The lithium based fires require 12-15 times the amount of water to extinguish.
Why is water being used for either? One's an electricity-rich fire, the other's an oil-rich fire, water's an unwise response to both for different reasons.
Although weirdly enough the video demonstration doesn't seem to be of a battery fire. :facepalm