sorry the tutorial isn't working for you. I'm afraid that one wasn't written by me, so I am not in a position to update it. All my tutorials are available on my blog at http://mark-dot-net.blogspot.co.uk/search/label/NAudio. I'm afraid I haven't done much on MIDI but I will bear it in mind for future blog posts. The best thing for now is to look at the source code for the NAudioDemo which contains simple working examples of NAudio in action.
Mark