The tutorial was done in an earlier version of Swift (like when it was in beta), so things may break often. Change the bang into ? and see if it works. The bang force unwraps, and the ? is for optionals.
That self declaration when dequeuing threw me for a loop when I initial did it as well. I had to work with Brad to troubleshoot it. Sometimes when you're working through tutorials and it's not working, try looking through the comments. It might help.
I just updated my code again. The prepareForSegue method needed to be changed when I updated it to work with Xcode 6.1.