Welcome to the forum.
As John T. points out, AVI is virtually meaningless on its surface. He has linked to some articles to give you a bit of background.
As the Flip cameras are evolving, this FAQ Entry might not directly apply to your model, but might also provide some background.
Which Flip model did you shoot this video on?
When you set up your Premiere Elements 9 project, did you select the appropriate Flip project setting? This is vital to working with this video format.