Great screencast. I tried to read through the Acme guide before but never quite got the gist of it. This reminds me of the Starcraft interface in that if you have excellent mouse twitch reflexes it seems you can more easily induce a sense of flow (whether you're productive or not is a different matter; see APM spam[1]).

Definitely not an environment to work in if you have cats/kids that like to fiddle with your mouse when you're in the kitchen or taking a bio-break.

[1] http://en.wikipedia.org/wiki/Actions_per_minute