RENAME

@echo off
setlocal EnableDelayedExpansion
for /f "tokens=*" %%f in ('dir /b *.mkv ^| sort') do (
    SET var=%%f
    rem move "%%f" "2%%f"
    rem move "%%f" "1!var:~3!"
    rem mklink /h "2%%f" "%%f"
    rem if  "!var:~7,1!" == "_" move %%f "!var:~0,6!0!var:~6!"
echo "3!var:~0,2! !var:~4!"
move "%%f" "3!var:~0,2! !var:~4!"
)

Pause>nul
exit /b