I wasn't playing dumb. I may BE dumb, but I hope not in the case under discussion. One of us certainly was, it seems. You may be disappointed to find that not
everything on the internet is true, and in this case you seem to have stumbled onto the site of a complete numpty who is as ignorant of simple chemistry as a sparrow.
That wasn't Lithium in the video you showed. It was sodium. You can tell in two ways
1. The lithium-water reaction is much gentler, and ignition doesn't take place as it does with the other alkali metals.
2. The flame was orange-yellow - characteristic of sodium. Lithium burns with a scarlet flame
You can find plenty of further good information on the net, in a few seconds, such as this for instance:
http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_pre_2011/periodic_table/group1rev3.shtml
Lithium fizzes fairly vigorously and gives off hydrogen and slowly gets smaller until it vanishes but it doesn't get hot enough to autoignite. Sodium shoots about the surface of the water and the reaction is exothermic enough to ignite the hydrogen and you get an orange flame. Potassium is even more dramatic. It autoignites immediately giving a bright lilac flame followed by an explosion! The Lithium - water reaction lasts longer than the others BECAUSE it is gentler! You may also be interested to learn that LiOH is a much less 'strongly alkaline' base than NaOH or KOH. which also conflicts with what you imply in your post.
The danger in lithium batteries is that a short circuit or overcharging can cause them to heat up to the point where they go on fire. I understand that the electrolyte is also inflammable, and once the casing of the cell bursts open you have a vigorous fire on your hands. It is not easy to put out by water, and squirting water over it will generate hydrogen as well as failing to cool down the reacting lithium.
Batteries are a huge pain in the backside. I hate the idea of building into systems, components which have limited life, are expensive, costly, often dangerous, bulky, and have to be worried about and looked after and replaced. Life without them would certainly not be bleak! Why not be really optimistic, and look forward to something better such as Fuel cell or capacitor powered cars.
However, it is also worth remembering that there are no guarantees that the universe is constructed in such a way that we can have exactly what we want. It may NEVER be possible to construct a battery with the energy density of a simple tank of diesel.