I tried a lot of programs to rip DVDs to my BlackBerry (8320), and the only one that gave me consistent success was the Aimersoft DVD to BlackBerry Converter. I've ripped over twenty DVDs to MP4 files and watched them with no problems.
After I upgraded my handheld software to v. 4.5.0.81, when I try to play the files I get audio only, but no video. Plus, when I'm playing a movie (and getting only audio), I can pause the playback and restart it at any time. But if I stop the playback, my phone does a full reboot.