$ cat mylist.txt
file '/path/to/file1'
file '/path/to/file2'
file '/path/to/file3'

$ ffmpeg -f concat -safe 0 -i mylist.txt -c copy output.mp4

# The -safe 0 is for recent ffmpeg versions complaining about Unsafe file name
# https://stackoverflow.com/questions/7333232/how-to-concatenate-two-mp4-files-using-ffmpeg