All great suggestions. I would also add the following:
Books:
"Guerrilla Jiu Jitsu: Revolutionizing Brazilian Jiu Jitsu" by Dave Camarillo
"Brazilian Jiu Jitsu: The Closed Guard" by BJ Penn
DVDs:
"111 Half Guard Techniques" by Caio Terra
"Brazilian Jiu Jitsu: No-Gi Essentials" by Roy Dean
"The Triangle" by Ryan Hall
"The Science of Jiu-Jitsu" by Demian Maia
"Escapes!" by Bill Cooper
"Sambo Jiu Jitsu Fusion Vol. 1: Throws and Takedowns" by Vladislav Koulikov
YouTube channels:
Beyond Grappling
Kurt Osiander's Move of the Week
BJJ Video Vault
BJJ After Forty
BJJ Library
MMA Leech
If you have to pick just one, I'd go with "Jiu Jitsu University" by Saulo Ribiero as suggested by CowboyJD. It's organized into sections by skill level (white belt, blue, purple, brown, and black) and goes over what you need to survive your first few months and progresses from there.