Also deal with multiple part items on item list.
Since Windows doesn't easily support symlinks and / or hardlinks, don't use them, and instead let the buffer file have a name we know will please Plex's scanner.
Give the buffer file a name that Plex will like without messing about with symlinks / hard links later on. This is most for Windows' benefit.

And correctly set Binary flags on file open. Also for Windows' benefits.