Read Bill Hunt on a file type as WRAPPER http://forums.adobe.com/thread/440037
What is a CODEC... a Primer http://forums.adobe.com/thread/546811
What CODEC is INSIDE that file? http://forums.adobe.com/thread/440037
Report back with the codec details of your file, use the programs below... a screen
My guess would have been Xvid, or DivX (the commercial version of Xvid).
Unfortunately, PrE is never likely to Import and edit files with those CODEC's. I would choose another option, or plan on converting the Xvid material to DV-AVI, or to something that PrE can edit.
I use an older, shareware conversion program, DigitalMedia Converter 2.7. Deskshare has issued newer versions, including a "Pro" version, but I have not used anything since 2.7.
The FAQs to the right of this forum offer a list of programs, and which settings to use, to create edit-compatible DV files. You can't just output an AVI and expect it to work! As John and Bill point out, there are thousands of possible AVI codecs!