I would do it something like this:

use strict;
use warnings;

sub slurp
{
    my $file = shift;
    open( my $fh, '<', $file ) or die "error: open '$file': $!\n";
    local $/ = undef;
    my $s = <$fh>;
    close($fh);
    return $s;
}

my $file = shift or die "usage: $0 filename\n";
my @m = slurp($file) =~ /^=begin[^\n]*\n(.*?)^=end/msg;
print "---\n$_---\n\n" for @m;
[download]