A command-line tool that allows for lossless merging (concatenation) without re-encoding, meaning zero quality loss. This is ideal for identical clips from the same camera.
Lossless merging (supported by FFmpeg) is nearly instantaneous because it simply copies data. Re-encoding takes longer but allows you to join clips with different settings. How to merge two or more video files in Microsoft Clipchamp merge vcmp4
Depending on your skill level and operating system, you can choose from these popular options: A command-line tool that allows for lossless merging
While primarily a player, it has a "Convert/Save" feature for merging. Note that it works best when all videos share identical formats, resolutions, and frame rates. and frame rates.