I don't believe there is a way. But, if your doing multimedia this year and your teacher is a marker, then u may get lucky and be able to find out your mark relatively accurately.
My taecher said that this year he might be able to take some of our works to a 'practice marking' a few days before the actual marking. This is where the markers have to get together to do some practice marking to ensure that all markers are marking in the same manner (blah!). If you can try to get yours chosen for this as it will give you a pretty accurate idea of what sought of marks you'll get.
Just thought i'd mention it..........sorry, that doesn't help you guys that have done it already much