how easily do Lithium Polymer (LiPo) batteries catch fire? 2. charge state

DANGER - DO NOT TRY AT HOME - SAFETY FIRST
0:00 - a puffed but charged cell
1:02 - puffed buty partially discharged
1:16 - puffed but discharged

A safety video showing just how easily these common Lithium Polymer batteries catch fire and explode. I do this so you don't have to.
These batteries are in phones, drones, cameras, laptops etc etc they are the standard small grey packs - it becomes quickly obvious why airlines and postoffices don't like them (the fire can burn through aluminium tubes)....these had puffed so although showing 4.2V carried little actual current but as can be seen it's more than enough to set fire to anything in your house after burning you and filling your lungs with toxic smoke.
As can be seen the critical aspect to LiPo safety with regards to physical damage is the charge state, charged batteries explode, discharged ones don't (the charged one could still boil water 5 mins afterwards).
When handling, storing or scrapping LiPo batteries ALWAYS discharge them first.

As we move into the Electron Age be very careful, 1 electron does little on its own but when you move loads of them they can deliver huge amounts of power.

and yes i mistakenly stored fully charged LiPo batteries for my drone when i moved house and it killed all 3 battery packs....over £120 made useless by laziness....discharge before storing or they puff and there's no way to vent afetr this, they are (were) knackered.