I just made a ribbon scarf and had the SAME problem.
The written directions say to knit every loop. The videos say, and show, knitting every other loop (or even more if you want really loose and baggy).
What I found is that you MUST knit every other loop. If you knit every loop you will get a scarf that just has tiered layers, that lay flat on top of one another. By knitiing every other loop you will get ruffles.