Oh, my! I was looking for a visual on the mitered corners. This might or might not be the answer for you - but LOOK at the way she says to finish the binding!!! I'm always twisting my binding when I try to finish it off in a continuous piece with a diagonal seam. I can do it, but it often takes multiple attempts. This looks like the answer to my prayers!!
http://www.kayewood.com/tips/bindings.pdf
This video is gadget heavy but still rather interesting:
http://www.youtube.com/watch?v=DVuQ0eiRS8U