Since there is no public documentation for a standard tool with this exact name, it is highly likely a or a batch command utilizing a media engine like FFmpeg . Technical Breakdown of the Process

: Automated scripts often merge files in alphabetical order. If the files are named 1.mp4 , 2.mp4 ... 10.mp4 , some systems might sort them as 1.mp4, 10.mp4, 2.mp4 .

: Most scripts of this nature use the FFmpeg Concat Demuxer . This method is "lossless" because it copies the data streams without re-encoding them, provided all input files have the same resolution, frame rate, and codecs.