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GitHub User: rabidpraxis
I must say that I completely disagree with these latest sentiments. I think that every developer should spend time understanding the tools that they use (which INCLUDES reading the source code). I don't consider developers who use rails to be exempt to this.
Rails is complicated and intertwined (as you can see from the screencast). Most people, when first viewing the code get overwhelmed quickly. These walkthroughs show how you should read through source code and put together the pieces to gain an understanding of how things are put together.
I, for one, applaud the effort spent on more 'advanced' screencasts.