How to merge lots of videos into one with ffmpeg on Windows...
Put this into a .bat file and smoke it:
REM https://stackoverflow.com/a/41387530/1028230
:: Create File List
for %%i in (*.mp4) do echo file '%%i'>> mylist.txt
:: Concatenate Files
ffmpeg -f concat -safe 0 -i mylist.txt -c copy output.mov
Obviously use a full path to ffmpeg if it's not in your PATH.
I got errors when trying to save out to an mp4, but not when saving to .mov.
Actually I got errors for .mov, too, when combining Wyze cam videos like this, but the resulting file still opened fine.