What does not work

ffmpeg has an insane interface for simple use cases like joining two MP4 files.

cat draw.mp4 draw2.mp4 > draw3.mp4

ffmpeg -i "concat:draw.mp4|draw2.mp4" -c copy draw3.mp4

ffmpeg -i draw.mp4 -i draw2.mp4 -vcodec copy -acodec copy draw3.mp4

mkfifo temp1 temp2
ffmpeg -i input1.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts temp1 2> /dev/null & \
		ffmpeg -i input2.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts temp2 2> /dev/null & \
		ffmpeg -f mpegts -i "concat:temp1|temp2" -c copy -bsf:a aac_adtstoasc output.mp4

What works

ffmpeg -f concat -i <(for f in *.mp4; do echo "file '$(readlink -f $f)'"; done) -c copy output.mp4

With a different sort:

ffmpeg -f concat -i <(for f in $(ls -1 | sort -r); do echo "file '$(readlink -f $f)'"; done) -c copy output.mp4