for( map{ s/\\*([^\\]+)\.avi\n/$1/; $_ } `cmd /c dir /s /b *.avi` ) {
   $inventory{$1} = $2 if /^(.*?)s\d{1,2}[xe]\d{1,2})/i);
}

# BROKEN OUT -- follow the numbers
for( map{ s/\\*([^\\]+)\.avi\n/$1/; # 2: isolate filename between last
                                    #     backslash (if any) and newline
          $_ }                      # 3: pass on $_, not result of s///, which is the
                                    #     number of replacements made
     `cmd /c dir /s /b *.avi`       # 1: get avi files, including sub-dirs.
                                    #     dir is a shell (cmd) command, so
                                    #     you might need to call it this way.
)
{
   $inventory{$1} = $2 if /^(.*?)s\d{1,2}[xe]\d{1,2})/i);
}