: Best if your files have the same encoding settings. You can "append" files sequentially and save the output without re-encoding, which preserves original quality. Mobile Apps (Android)

If you are joining multiple clips, they ideally should have the same resolution and aspect ratio for the best final look. Merge MP4 Videos: Combine MP4 Files for Free Online - Adobe

To "put together a piece" using video files like 0guqd3oqmm0rliy2v2qjp_source.mp4 , you can use various free tools and methods depending on your device and desired complexity. Online Tools (Quickest & No Install)

These are ideal for simple merging without downloading software:

: Open iMovie, start a new "Movie" project, and select the clips from your library. You can then tap "Create Movie" to join them instantly.

: Search for "Video Editor" or "Photos" in your search bar. Start a "New video project," add your MP4 files to the library, and drag them into the storyboard to arrange them.