Easypreview.bat

set /P f="File: "
set /P o="Output File (no .webm): "
echo "Preview time - FrameTime == 01:05 - Preview from 1m 5sec"
set /P t="FrameTime: "
ffmpeg -ss %t% -i %f% -vframes 1 -c copy -an -y TEMP_%o%_preview.webm
@echo file 'TEMP_%o%_preview.webm'>nul>>%o%.txt
@echo file '%f%'>>%o%.txt
ffmpeg -itsoffset 0.04 -i %f% -f concat -i %o%.txt -map 1:v -map 0:a -c copy -y %o%.webm
del TEMP_%o%_preview.webm
del %o%.txt