I see that you are a windows usr.
1st - i would suggest linux ( i could expand on the benefits )
2nd-
try something like this in a file.bat
@echo off
cd <path to your mp4>
for /f %%a IN ('dir /b *.mp4') do (
<path to your ffmpeg.exe>ffmpeg.exe -i %%a -y < your ffmpeg cmd
instructions of choice> <out>%%~na_frame%d.png
)