okay so maybe my tutorial wasn't as good as i thought. saw a GF tonight who mentioned it was a little vague so i will clarify.
begin your braid with hair divided into two sections. instead of weaving three sections together like a typical braid, the fishtail braid you only weave small pieces from the two sections. take a small piece from the left section, and pull it over to the right. next take a small piece for the right section and pull it over to the left. if you are french braiding the fishtail, you will do this as well as pick up extra hair with each pull. i suggest beginning at the nape of your neck to practice and once you get it down, attempt the french braiding.