The pattern movXXXXX.avi is typical for that use automatic file numbering. MOV often indicates a video container format (though .avi is another container – the mix is unusual, but possible if software renamed it). The number 00004 suggests it was the 4th video captured in a sequence. The word new could be:
: A cross-platform open-source application that decodes almost any legacy AVI stream natively. mov00004 avi new
ffmpeg -f concat -safe 0 -i list.txt -c copy output_joined.avi The pattern movXXXXX