iPhoto 5.0 Problem: Can't Import AVI Files

Upon trying to import some AVI files into iPhoto, I got the following error message:

Unreadable Files: 1

The following files could not be imported (they may be an unrecognized file type or the files may not contain valid data).

/Users/vincentpace/Desktop/RMOV0001.AVI

This is particularly puzzling because Quicktime Player opens the movies with no problem. Moreover, previous video clips that I've made on the same camera with the same settings (I've never touched the video settings) have been imported, although these are the first ones that weren't on my computer before I installed iPhoto, although I can't see how that would be relevant.

A quick google search reveals that this error message has come up before in earlier versions, but all the fit-its are for pics and not videos, so I'm not sure what to do. If anyone has a clue, please give me a hollar.