LPArchive.org has added 93 video guides of Valve's Left 4 Dead 2 to their vast archive. Here's a list of the campaigns that's covered in those video guides:
All of those video guides was created by baldurk, Blister, cKnoor, and EthanSteele. Thanks for your awesome work guys! Click here if you're looking for a video guide for the first Left 4 Dead title.