Without prior downloads happening before going offline I’m not sure you could share a file between mobile operating systems out of the box, regardless of which

Without prior downloads happening before going offline I’m not sure you could share a file between mobile operating systems out of the box, regardless of which OS is trying to supply the file. If I’m allowed to pre-download software before encountering your scenario, running a web server or an app that serves FTP or other server types hosting files is trivial on either OS. iOS may require shuffling the video file into an app sandbox first.