Elbows Music Blog Community

I wanted to add another category to one of my posts, but it changed the permalink as well. Now when I try to get to the post (http://silencenogood.net/documentaries/hyphy-movement-story/) it redirects me to the new permalink which redirects me to the old and finally just errors out (try it). Someone recommended I just create a new post for it, but I have some comments on there. Is there anyway I can correct this without making a new post? Also, is there a way I can add a second category without changing the permalink structure?

Thanks, I have no idea how to fix this :(