[Kalimac]

Depends on how you define magic. Galadriel tells Sam (when he asks if her mirror is magic) that she finds that a hard term to understand, since he seems to use it both of her works and of the works of Sauron. All it really would have to mean in this case is a technology which they don't understand and are incapable of reproducing; in this case the cloaks and the rope. I'm sure the rope and cloaks will behave as they did in the book, maybe with a little CGI to make the cloaks hide the wearers a bit more perfectly than ordinary cloaks would, but it may not look terribly spectacular to the moviegoers; after all, there's nothing inherently exciting about seeing a rope slither down or NOT seeing someone in a grassy landscape. It's only by knowing that the rope somehow untied itself, or that there was a person there who was completely hidden by a cloak, that the magic comes in.