You need to use a dvd to AVI converter to help you. BestHD Blu-ray To AVI Converter is what I am using. It can convert almost all kinds of DVDs to AVI format(AVI-H264, AVI-DivX, AVI-XviD, AVI-MPEG-4, AVI-MS MPEG-4, AVI-MPEG, AVI-WMV )
Check it out at:http://www.besthdsoft.com/blu-ray-to-avi-converter.html
It ensures fast converting speed with good quality. With only 3 steps, you could easily convert your movies to AVI format
step 1. click "Add Blu-ray" to add your movies
step 2. select output format from "profile" list
step 3. click "Start" button to start conversion
Done.