The substance that you see in the video that is being added to the undrinkable water is known as polyglu. The UN uses polygue to treat undrinkable water in the regions where clean drinkable water is inaccessible.
Polyglu is merely a coagulant. It will separate many solids from the undrinkable water. Once the water is clear you can actually leave it in direct sunlight for 6 hours in a clear glass or plastic bottle to make it potable.This same Chemical is used in treatment plants.