Streaming video has become a major part of how film studio's go to market, which is why Disney is interested in starting its own service. Content is king when it comes to success, and for Disney that will mean having as much material that people will want to watch as possible. The addition of Fox will greatly help in that regard, though the fact that Fox has an existing deal with HBO may mean that a lot of content that would otherwise end up on Disney's streaming service may not show up for a few years. While HBO traditionally has a particular window in which it releases films, there's always a handful of older titles also available on HBO Now. Depending on exactly how the Fox and HBO deal is constructed, Fox movies will, at the very least, show up a few months after a Disney film with a similar theatrical release.