Infinity Ward scripter (now at Respawn) Mackey McCandlish is doing walkthroughs of stuff he worked on starting from CoD1. Some really insightful information both tech and design wise on how CoD came to be and is designed – you just have to be patient with him dying a lot (especially in Chateau), but he gets better in later videos.

Chateau -- CoD1 prototype / pre-proof of concept level for making a WWII game.
http://www.youtube.com/watch?v=U_yN78JOhZU&hd=1

Burnville -- CoD1 proof of concept for scripted events and traversals.
http://www.youtube.com/watch?v=kKz7YKUtHAA&hd=1 (Part 1)
http://www.youtube.com/watch?v=CVVL8cz-LOA&hd=1 (Part 2)

Stalingrad – CoD1 creation of the Drone system and how to create compelling scripted sequences without taking control away.
http://www.youtube.com/watch?v=RVF3gomI_qQ&hd=1