Before joining, ensure your files share the same technical specs for the best result: : Most modern MP4s use H.264/AVC.
: If you have many pieces and want to join them without losing quality (lossless), use the FFmpeg command-line tool. You can use the "concat" command to stitch files with the same codec (like H.264/AVC) together instantly.
To "put together" or combine video files like "2776.mp4" (assuming 2776 is a file name), you can use several free and professional tools depending on your technical comfort level. Recommended Methods for Joining MP4 Files