Step 1 : Install DVD to iPhone Converter Suite from Cucusoft. The main program window will open, which contains the basic controls for converting your DVD to iPhone 4 -compatible video file. Click "DVD" to run DVD to iPhone Converter.

Step 2. Insert a DVD to your DVD drive. Click "Open DVD"

Step 3: Choose profiles from the 'Profile' drop down menu. H.264 is supposed to have better compression for the same quality as mpeg4.

Step 4: You can also choose to crop the black bands of your movie to decrease its size. Be carefull since some movies place their subtitles on the bottom black band. If you don't need any subtitles you can crop both bands.

Step 5: Choose the directory into which the file should be saved by using the “Output” menu.
Step 6: Hit 'Convert' button, choose the recording time point and quality, then click 'Yes' to begin to convert DVD to iPhone 4 video or audio quickly.

Now you can use iTunes to copy the video file to your iPhone 4 and view it anywhere you like!
Free Download Cucusoft DVD to iPhone 4 Converter Suite! 
Related Guide: Video to iPhone 4