These are XML chapter files to add opening and closing chapters to Sword Art Online - Alicization - War of Underworld, You need this software to to add files to videos: https://mkvtoolnix.download/ . I am putting a link instead of adding the software because most people like to avoid exe files from torrents. This will probably work on any SWO download as long as it doesn't have anything added [like anime site rips]. just to be safe, I would use HorribleSubs videos for these files! If you haven't downloaded the the videos already, check out my other torrent: https://nyaa.si/view/1281922.
Edit: If you already have another MKV video editor, I would check to see if you can add them with it, since the one I linked is the only one I know.
Edit 2: sorry, Seems my torrent engine is prioritizing my other torrent over this one, once it has a few seeds, I'll take it out of super seeding mode to give this torrent a bigger priority. Unfortunately I don't have as much bandwidth as other uploaders.