About 15-20 years ago, when DVD-s for saving/writing movies were not available everywhere,
this was the normal way to show/save a full movie for CDs - in two parts (splitted).
2H movie/video saved on 2 CDs...
As I remember - most JAV movies at website
Adultdailycare.net, years 2008 - 2012 were in two parts.
I was and am now using the FREE
Avidemux tool for merge two parts of videos/movies, works great!
Usually those splitted movie parts have the same resolution, bitrate and frame rates.
This Free and simple program could be downloaded at
Avidemux home page -
Avidemux download page. Get v2.8.1 stable and v2.8.2 nightly builds. Free, lossless video editing for Windows 11, macOS Sequoia (M1/M2/M3), and Linux AppImage.
avidemux.net
In Youtube is a useful guide how join/merge video files.
Or - shorter video - without comments, just - what to do...