I think I attempted to configure Multimame once and it seemed too technical at the time so I abandoned it. I ended up finding another version of MAME that solved my problem so there was no need to pursue it. If I recall, you needed to edit XML files to configure Multimame.
As far as the snaps go, I haven't tried it, but theoretically, you shouldn't have to do anything since your are pointing to the Multimame executable in Maximus Arcade. Nothing else changes; so the snaps and video directories remain the same.
I wouldn't mind messing with it again though. Perhaps we should start a new thread with the subject: "Using Multimame in Maximus". Then we can post various configurations and contents of the multimame.xml files. Thoughts?
D