Why it's not a great idea to charge large unbranded lithium batteries in your living room

In this footage, a man is seen relaxing at home when a nearby battery, apparently charging on the floor, starts spraying sparks. It explodes violently as he approaches to unplug it. The origin of the footage is unclear: the video is being ganked on every video platform and none of them bother to report any information whatsoever. So I don't know if the person is injured or how badly the dwelling was damaged. He is at least able to fetch a fire extinguisher and have at the blaze.