there are a couple of ways I can think to do it...
1) install Quicktime player 7 from your OS disc, and export from it (The QT 10 won't work)
2) Download Handbreak and convert the AVI to a QT movie from or any current format, then just import into Logic.
The issue you have is the AVI is not native to LP9. That and the fact that the Logic 9 manual is about as clear as a swamp when it comes to this kind of stuff other than the basics.
While I love the new mini manual for Logic Pro 9 , the one in the packaging, I wish they would actually create a users guide like that for the main stuff in Logic, a more advanced on. the mini manual as is is for beginners, but it is fantastic.