I just bought on mbox. I would have paid the extra money for 9 but my xp machine cannot run it.
My understanding is that 9 will work with any brand of interface and so it seemed to make more sense long term to go with 9. It also has different (better?) plugins.
I have to agree, the knowledge you are seeking has been given by several posters. Maybe you should post your question on youtube if all you want to know is what video you saw.