So I did a little searching and figured these were from the Blu-ray box ([this](https://nyaa.si/view/728916) one), on disc 9, files `00007.m2ts`, `00008.m2ts`, `00021.m2ts`, and `00022.m2ts`. The file sizes were the same. Downloaded those files, renamed them, opened this torrent, and hey presto, it started seeding.

Thank you for saving me the trouble of digging through a bunch of m2ts files.