This is a very nice and short tutorial.
the gist of it is, you take a piece of sewing thread and twist it just so, put your unwanted hair ahead of the twist to catch the hair, and the hair is pulled out. It seems cool because it is very precise and you don’t have to pay for wax or tweezers.
I must have done it wrong because the woman in the you tube video has thicker hair than me (harder to pull out I assume) and her eyebrows look great! When I tried it and all it did was make my unwanted hairs very curly.