Then "18" and "portable". The "18" could refer to the movie's rating in some countries, which is equivalent to R in the US. But in this context, maybe it's part of the file name or version. "Portable" usually refers to a version of a software or file that's easy to carry around, like a portable app that doesn't need installation. Applying that to a movie, maybe it's a compressed or smaller version for easier downloading or storage. However, using the term "portable" in this context might be a bit of a stretch. Alternatively, it could be part of the file naming convention.