I have an avi file that is coded with DivX version 5.05 and when I choose "Read Files" it didn't add the "DivX5" in the "Codec:" field on the "Media" tab. I've tried and read other DivX 5 files and it works ok but I don't know the exact version of DivX that was used for creating those files unfortunately
I've sent a small sample of the avi file (1,4MB) to you Alessio and maybe you could try it