I'd be interested to see what value this adds compared to the documentation and existing (free) blog posts on it's use. IMHO Backbone's docs are super friendly and if you're really wondering what's going on under the covers the source code is relatively easy to jump into and understand (assuming you're a javascript programmer not a jQuery hacker)
I agree about the Backbone.js docs being quite awesome. I think they get a bad wrap myself. But I've also found that some folks like the option of watching screencasts to learn about certain topics as well.
I kind of fall into both categories. I really like reading the docs (and more importantly, the code itself) as well as watching someone demonstrate certain topics. I guess I'm weird like that. :)