The nicest thing about RailsCasts, for me, was ASCIIcasts - I'm sure I'm in a minority, but I've never had much time for watching videos or listening to podcasts. GoRails seems to lack that, but perhaps for the majority that's a non-issue.
I write my scripts out when I do my videos. It helps me prepare the lesson plan. I place all the code I'll type in there too. Then I record. And then if I deviate from my script, I can just fix it up. It doesn't need to be a 1:1 thing.
But I find that this really helps speed up the process because I have a plan in place, and the script can easily turn into the transcript.
Just thought I'd share to see if there's anything you can steal from this process.