Download_railscasts is a project mainly written in Ruby, it's free.
Script to download all of the Railscast episodes
This script parses an RSS feed and grabs the Railscast videos that you're currently missing.
Downloads .mp4's.
To run, jump into the directory with Railscasts.rb, then:
ruby ./Railscasts.rbIt will download all of the videos into the directory you are running the script in.
Credit goes to Maximiliano Guzman.