The problem is that although port 80 is reachable, I have no idea how the communication works; perhaps I should just check the NAT tables.
Meanwhile, here's an email that I've just received
Hi XXX,
We have check with our Product Management team about future compatibility between the D-View Cam software and the DCS-8000LH cameras. The DCS-8000LH model will not be supported in D-View Cam for remote viewing or recording.
-- 
Best Regards,
Customer Service Dept. 
Service à la Clientèle. 
D-Link Networks 
2525 Meadowvale Blvd 
Mississauga, Ontario 
L5N 5S2