There are two approaches. Journalists can apply to have access to picture libraries run by Universal Studios and other film makers, where you can download images for the movies they want to promote. You just have to search for the Production company and find their PR/ Media resources to get access to their image libraries, with full permission.

The other approach is 'fair use' where the law allows you to use images for reviewing a product, like a book cover. I wouldn't worry about using a book cover for a review. I'm not so sure about movie shots. I'd imagine it's OK, but I'm not a lawyer. It's a judgement call. Expect Netflix can confirm this. They might have a picture library of their own, you can access.

That's a different issue to using creative commons images.