As a writer, I'm almost always playing scenes in my head. When I walk the dog, lie in the bath, settle in for a kip on the sofa, or even when I'm brushing my teeth. I constantly play around with my characters and what happens to them in my head.
So, what's the movie bit about? I see my scenes as scenes in a movie.
I visualize what happens in them from the backgrounds and environments (place), to the characters (people), to the conflicts, dramas, and happenings. I even choose actors to play my characters...
For me, each scene must have a beginning, a middle and an end. There must be something distinctive that moves the story along in every one. It doesn't have to logically follow from the previous scene, but it must be relevant to the story progression.
To get a good idea of this, watch a movie and note what happens in each scene. Summarise what the scene is about in 1 or two short sentences.
Then read through it and see how the story is moved along through the different scenes. A scene shows you something that is integral to the story... it doesn't have to tell it.
The book that gets you turning those pages at speed is the one that has the inimitable hook at the end of the scene. Peter James is a master of this. I've been reading a lot of his work lately because it hooks me in from the start, and I struggle to put it down until I've finished. The secret to a good hook is that it raises a question, the answer to which has serious consequences for the subject/character. I can practically see the dilemma they face and have to read on to find out what happens.
Are you making movies in your head whilst you write?