Haha, cool idea
Is Cephalopodomancy a real word or made up?
I've always seen the films (and actually film adaptations in general) as a kind of "moving-illustration" of the books: a chance to see the characters, settings, and a couple of your favorite scenes in animation, but no more. There will always be lots of missing scenes and forgotton characters but that's what happens with films. It will never be 100% faithful and you've just gotta learn to live with that. They add something to the overall experience of the books and the world JK created, but could NEVER replace them entirely and they're not meant to. I think people forget that sometimes. Sorry if that sounds like a rant, I'm not having a go at you personally lol, just at people who hate the films because they're not identical to the books.
Personally, I'm REALLY excited for DH, because even if there are parts that suck, it's still Harry Potter, it's still the world I love, and it wont be the end of the world because we'll always have the books