Use the Canon MP4 Join Tool for Windows or macOS. It’s designed specifically to merge split files without losing quality.
To do more than just join clips, such as adding text or trimming parts: g61029.mp4
If the file is corrupted, you might need a repair tool like Fix.Video or Handbrake to re-encode and "heal" the file structure. 4. Renaming & Organizing Use the Canon MP4 Join Tool for Windows or macOS
mp4 . Whether you need to join it with other clips, edit it, or just figure out why it won't open, 1. Combining with Other Clips g61029.mp4
Is this file part of a from a specific camera, or are you just looking for a way to edit/trim this specific video? How to combine videos - Microsoft Support