I've been working on recreating Hermione's Scarf from the same Harry Potter and the Half-Blood Prince publicity still I used to make Hermione's Hat. I think the stitches are right, but the gauge in the publicity still is strange, with stitches taller than they are wide. I'm hoping to be able to block it that way. If not, each row could be doubled to create a similar effect.
I've also decided that even though it's obvious that Hermione's scarf slowly rotates colors, I'm going to keep my pattern a bit simpler with the same motifs always using the same colors. Knitters could always knit it however they like. With any and as many colors as they like. Without being able to see the whole scarf, I don't want to guess at a pattern. As it is, one of the 3 motifs is partially hidden, and I had to take an educated guess with it. There may also be more motifs that cannot be seen in this still. So obviously this will strictly be my interpretation of it.
My colors here are obviously different that Hermione's. I'm being a good girl and using my stash. :) Later I'll seek out the proper colors, perhaps even selling the pattern as part of a kit!