Excuse me, I've overlooked that line.

What is your OS? What shows 'which echo' on your system?

This code works pretty well on my system:

#!/usr/bin/env perl
use strict;
use warnings;
use 5.010;

my $url = '"www.youtube.com/watch?v=mark"';
system('echo', $url);
$url = "www.youtube.com/watch?v=mark";
system('echo', $url);
[download]

McA