Original post by: bac ,
you could use an analog to digital video converter box. One of these would let you convert the composite video output of the Wii to digital video over Firewire to your Mac and import into iMovie. I have an old Canopus AVDC (model 100? or 110, I forget) converter box which I use to import Hi-8 analog video to digital, perhaps something like that would work for your purpose?