"Bringing Left 4 Dead into your marketing mix also brings in the expectations of Left 4 Dead, thus opening yourself up to a lot more criticism." -Adam Sessler (G4TV)

All B4B gameplay is patched and recorded post-launch.
All L4D1 clips have been recorded on the original L4D.
Thumbnail, Francis intro, and 20∶35 were made in Garry's Mod.

L4D1 modding tools released six months after launch: https://www.l4d.com/blog/post.php?id=...
L4D2 modding tools released one month after launch: https://www.l4d.com/blog/post.php?id=...

--- Interviews ---
Game Informer    • Life After Death: The History of Turt...  
thegameawards    • Back4Blood World Premiere Trailer and...  
IGN    • Left 4 Dead - New Survivors Trailer  
TheWeeklyBlend    • Left 4 Dead Interview  
Game Informer    • Back 4 Blood Dev On PVP, Microtransac...  
IGN    • Back 4 Blood Dev Interview: Breaking ...  
Gamespot    • Left 4 Dead 2 - Gabe Newell Interview...  
GameTrailers    • Left 4 Dead Story and Undead Playabil...  
G4TV    • G4TV Hands On: Left 4 Dead E3 2008  

--- Ending sources ---
Mega64    • Mega64: The Beatles Rock Band  
IGN    • Left 4 Dead Xbox 360 Interview - Kerr...  
Techniche    • Techniche Interviews'17 : A Conversat...  
Gamereactor    • TGS09: Left 4 Dead 2 interview  
GDC    • Valve's Physics for Game Programmers  
GameTrailers    • Left 4 Dead - GTTV Extended Preview  
Steam Dev Days 2014    • Data to Drive Decision-Making (Steam ...  
IGN    • Valve on the Future of Half-Life Plus...  
GDC    • AI-driven Dynamic Dialog through Fuzz...  
Inside Xbox    • 東京ゲームショウ 2009 『Left 4 Dead 2』インタビュー (...  
Esports in a Nutshell    • Valorant Art Director Moby Francke ta...  
LICAF    • Bay Raitt Interview  

--- Mods at 22∶30 ---
Common Madness https://steamcommunity.com/sharedfile...
Cat Gun https://steamcommunity.com/sharedfile...
Nick Dimmadome https://steamcommunity.com/sharedfile...
Chef Coach https://steamcommunity.com/sharedfile...
Fall Guys https://steamcommunity.com/sharedfile...
Halloween Rochelle https://steamcommunity.com/sharedfile...
Shirtless Ellis https://steamcommunity.com/sharedfile...
LOTR Campaign https://steamcommunity.com/sharedfile...
Space Skyboxes https://steamcommunity.com/sharedfile...
Halo Online HUD https://steamcommunity.com/sharedfile...
M9 Bazooka https://steamcommunity.com/sharedfile...
TR Survivors https://steamcommunity.com/sharedfile...
Halo 3 M90 Shotgun https://steamcommunity.com/sharedfile...
Halo 4 Energy Sword https://steamcommunity.com/sharedfile...
Chicken Pipebomb https://steamcommunity.com/sharedfile...
Overwatch Skies https://steamcommunity.com/sharedfile...

--- Songs ---
L4D - Menu Theme    • Left 4 Dead - Menu Theme  
L4D2 - Dead Center    • Left 4 Dead 2 Soundtrack - 'Dead Center'  
L4D - No Mercy Theme    • Left 4 Dead - No Mercy Theme  
HL2 - Triage At Dawn (slowed)    • Half-Life: Alyx - Final Hours - Triag...  
L4D - The Monsters Within    • Left 4 Dead Soundtrack- 'The Monsters...