Ein guter Anfang:
use strict;
use warnings;
use LWP::Simple;
use JSON;
use Data::Dumper;
# Beachte Parameter Since
my $URL = "http://apiv1.scribblelive.com/event/1065698/all/?Token=Q872zTYJ&format=json&Since=2015/9/18";
# JSON decodieren
my $struct = decode_json(get $URL);
# alle Schlüssel wo images enthalten sind
my @arrays = ( @{$struct->{Posts}}, @{$struct->{Deletes}}, @{$struct->{Edits}} );
# Filter auf Datenstruktur anwenden
my @media = grep{ defined } map { $_->[0]{Url} } map{ $_->{Media} } @arrays;
# hier sind nur noch die Image URLs
print Dumper @media, $struct->{Meta}{LastImage};
Das gibt aus
$VAR1 = 'http://images.scribblelive.com/2015/9/17/8a6a6a71-ef53-48fe-b2a2-29d16a273f95.jpg';
$VAR2 = 'http://images.scribblelive.com/2015/9/17/54e0d28b-cb76-4106-b3f0-b6cc5ff29c7a.jpg';
$VAR3 = 'http://images.scribblelive.com/2015/9/17/14602bfa-171c-4f96-81c7-b3b920675b38.jpg';
$VAR4 = 'http://images.scribblelive.com/2015/9/18/20ba73cf-7d2d-4455-af69-0f3d054efde1.jpg';
$VAR5 = 'http://images.scribblelive.com/2015/9/18/0d3d9d89-9b92-43c2-8df9-55e157c4c02d.jpg';
$VAR6 = 'http://images.scribblelive.com/2015/9/18/cb7794d0-c46e-4a28-9232-0e5c9bce9468.jpg';
$VAR7 = 'http://images.scribblelive.com/2015/9/18/7d3f2920-bafa-4ec7-ab75-e856f8c1fd97.jpg';
$VAR8 = 'http://images.scribblelive.com/2015/9/18/0c4ee31a-0098-4edd-aae7-73df249397da.jpg';
$VAR9 = 'http://images.scribblelive.com/2015/9/18/0d3d9d89-9b92-43c2-8df9-55e157c4c02d.jpg';
Zum Ermitteln der Image URLs. Ob der Parameter Token immer derselbe ist, KA. Anhand der Liste kannst Du dann das Download organisieren ;)