It starts off quite slow and a little confusing but it gets much clearer the more you watch - I watched the whole thing. Don't get me wrong though, I think it's a good effort and it's clear enough as long as you do stick with it. Thinking about your target audience is really important though. At the moment, I'd say that this is a little too quick for newbies but the CSS you show is pretty simple. You might need to break it down a little. Also, a task driven tutorial someone pauses and returns to works well.
I don't think you need to script every word, just having a good idea of the stages you need to do is enough. What you could do is record it in sections and then splice them together. Re-recording the audio would be easier too as you don't need to do the whole lot. I use Premiere to do this kind of stuff at work. We also use tools like Articulate to create menu driven e-learning. It packages powerpoints with audio and video as you want them. You lose the live typing (though you could easily import this once done in Captivate or somthing like that).
