Разобрался:)
#!/usr/bin/perl
use strict;
use warnings;
use WWW::Mechanize::Firefox;
my $mech = WWW::Mechanize::Firefox->new();
#my $id = "google-help";
$mech->get('http://www.youtube.com/');
sleep 10;
$mech->click({ xpath => '//button[@id="google-help"]' });
sleep 10;
