Comment by rrock

It wasn’t entirely clear in the parts that I watched, but my understanding is that slime molds are actually “social” amoeba. They often crawl around as loners, eating whatever they can find. But if they run out of food, they start sending out chemoattractants to all of their buddies in the neighborhood. They all crawl together and create a fruiting body (a spore) that eventually will break off in the wind and land somewhere else. Hopefully, in greener pastures. Those fruiting bodies are what you see in these videos. Amazing creatures, they live on the brink of multicellular eukaryotes.