@echo off
(FOR %%A IN (*.mp4) DO @ECHO file '%%A') > list.txt
ffmpeg.exe -f concat -i list.txt -c copy output.mp4
del list.txt
exit
ffmpeg.exe -f concat -i .\*.mp4 -c:v libx264 -crf 30 -preset slow -c:a aac -strict experimental -ac 2 out.mp4