A podcast is basically a show, either audio or video, that you download and put on your ipod. There are very many that are free, and even more that you can pay for. If you shop at the itunes store you can get tv shows, movies, and podcasts at a very cheap price, and some for free. If you need more info just PM me and I'll help anyway I can.
There is a way, how easy it is depends on your level of technical ability. You just download two programs. (I will state here that I am assuming that you are talking about DVD's that you own.) One is DVD Decrypter the other is Viedoera ipod converter. You run the decrypter first, then the converter. Most DVD's come out at just under 1GB. I've been averaging 800-900MB for mine.
As far as I know you cant just download DVD Decrypter for free anymore. I have a copy sitting around somewhere if you want it but I am sure if you spend some time on google you should be able to find someplace to pick it up from.