Cause iPod can play only MP4 format video, DVD movie is MPEG-2 format, in order to put it on iPod, you have to rip your DVD movie to MP4 format. I recommend Wondershare DVD to iPod Ripper to you, my friend recommend it to me, very easy to use and works great for me. This software can rip encrypted DVD movie to iPod format. what you need to do just put your DVD disk on your drive and start conversion, it will help you transfer DVD to iPod directly wihout iTunes, really help, you may download it for a trial.
http://www.dvd-ripper-copy.com/download/dvd-iP od-download.php?sid=2
Here is a step by step guide about this software
http://www.dvd-ripper-copy.com/forum/viewtopic .php?t=6
If you are Mac user, you can use 'handbrake', it's free and fit for Mac OS, here is the download link
http://handbrake.m0k.org
Here is a step by step guide about it
http://www.top5soft.com/tutorial/convert-dvd-t o-ipod-with-freeware.html
I hope it helps.