It sounds like AE does not recognise the codec associated with the AVI files.
I'm curious though. The MV730i is a miniDV camcorder right? It should produce DV AVI footage at (assuming it's the PAL version) at 720 x 576 pixels, 25fps, with either 16 or 12 bit stereo PCM audio @ 48,000Hz
The file properties associated with your AVI files in the AE program photo show numbers like 320 x 240, 12.5 fps, 16000 Hz, 16 bit Mono....
What the hell happened to your footage?
Did you capture the footage via firewire?