The Knowledge Is Power! is unlocked for listening to all in-game developer commentary which can be enabled when starting a new game.

Few things to note with this achievement:

• Listening to the commentary in full isn't necessary, they only need to be started.
  
• They all must be listened to in the same play session. Quitting or restarting the game from a new game or specific chapter will wipe previous progress.
  
• The achievement will immediately unlock upon starting the final track.

The easiest way to unlock this achievement is to load the final chapter of the game, backtrack downstairs through the previous areas triggering all the developer commentaries, then return to the top floor and take the baby to unlock the final passage with the last two commentaries.
This saves you redoing all the puzzles. Unfortunately most of the doors lock after picking up the baby, so that why you need to go downstairs immediately after loading the chapter.

I don't bother listing all their locations as they're all fairly obvious. Just use the list as a quick reference while backtracking through the game.

• welcome (1min 15sec)
  
• about (2min 46sec)
  
• the beginning (3min 17sec)
  
• the narrator (1min 50sec)
  
• cutting animations (1min 7sec)
  
• cinematics (3min 27sec)
  
• puzzles (3min 37sec)
  
• books (1min 46sec)
  
• audio (4min 10sec)
  
• making the art (6min 44sec)
  
• z fighting (2min 6sec)
  
• the grid (2min 15sec)
  
• performance issues (10min 2sec)
  
• lighting (3min 2sec)
  
• gwen (1min 50sec)
  
• flies (1min 43sec)
  
• plates and spoons (1min 39sec)
  
• character models (3min 10sec)
  
• the end (32sec)

If you're really having trouble finding one, I'll update them with the locations.