Convert all the .srt files that are Windows Hebrew encoded to UTF-8 keeping a backup copy of the original file with a .bak extension.

-i    - inplace editing
.bak  - generate backup with that extesion
-M    - load  module as 'use' would do
-p    - go over line by line on the file, put the line in $_, execute the
        command on it and then print the result.
        In case of inplace editing, save it back to the file.

perl -i.bak -MEncode -p -e "Encode::from_to($_, 'Windows-1255', 'utf-8')"

use Encode;

foreach $file (@ARGV) {
    copy $file, "$file.bak";
while (<>) {
   Encode::from_to($_, 'Windows-1255', 'utf-8');
   print $_;