I tend to frequently restart sentences as well. I have found that pushing myself to quickly get an extremely rough draft down makes me more efficient. This rough draft helps me focus my thoughts in the beginning on what I want to say. I can come back later and change how I say it.

If I don't do this--and I frequently don't--I find my output grinds to a halt with my brain both creating and editing sentences at the same time.

What are your thoughts on this?

Good for Etherpad. Features that enable narcissism often do very well. :)

However, I have to admit that I think such playback would make me a better writer.

I really like this evolutionary-way of writing. Small little improvements and changes until it sounds better and fits better to the rest of the paragraph/text/code. I found out that if i am disciplined enough when writing code this way the result is much much better. When i was working in corporate world there was always some distraction (boss, time constraints , ...) to break this flow resulting in not so good code.

I agree, I'm an obsessive editor and usually make multiple revisions to comments I leave on various blogs, HN, forums, etc. I should probably get in the habit of writing in a doc first, but I don't really feel like putting in the extra step for stuff that's usually rather trivial. If I was an active blogger, I would likely try to use this tool on a regular basis and link to it at the end of every post.

Thanks for sharing, very awesome to watch. My only request would be the ability to adjust the playback speed.

Was it Ian Fleming that said you should never start writing a sentence unless you know how it's going to end? It seems we're now in an age where sentences are started without knowing how they're going to start.

  There's other stuff I want to see that should be even more 
  interesting. When it's replaying, I want to be able to see 
  characters that make it into the final version in one 
  color, and others in another. Then I'll be able to tell 
  when I'm writing well and when I'm writing badly.

How about coloring text based on their age in the work? That is, characters added in the last edit are bright blue (or green), and as they age without changing, they fade to black. That would be extremely cool to watch.