I don't know if this will help, because it applies to v1 and I'm going from memory. You can only change the frame size when you export (i think eek
File>Export>Movie> click on the 'settings' button. In the 'General' section, change the file type to 'Microsoft AVI', then go to the 'Video' section and edit the frame size (you can also choose which codec you want to compress it with in the 'Video' section).
File>Export>Mpeg/Quicktime/Windows Media, you can edit the default settings on the left by highlighting one of them and clicking the 'advanced' button.
They might have changed all that in v2 though. wallbash: cry: