Nintendo and Apple seem to both ignite the same sort of passion in their customers, and I imagine that the Venn diagram that shows Apple users and Nintendo users has much overlap. Hence, I am sure many of you are trying to get movies from your Mac onto you Wii for your Wii viewing pleasure.
Riverfold Software has released Wii Transfer, a $9 app that will not only convert your movies into a Wii compatible format, but it will also move the movie file onto the SD Card of your choice (which must be connected to your Mac at the time). There is a 15 second screencast so you can see Wii Transfer in action on the Wii Transfer page.
If you're cheap (and judging from the comments we get whenever we post about some app a developer has the audacity to charge for, you are) MAKE has the skinny on how to create Wii compatible movies with a copy of Quicktime Pro (though if you are only looking to make Wii playable movies and you don't have a license for QT Pro, Wii Transfer is much more economical).
