Before you put the movies and videos on your iPod you need to convert them into a format that your iPod understands. Converters like Videora are available for free download. You can use such programs and convert the video before you use it in your iPod. A freeware that is used to copy video and music to your iPod is Floola. It is a cross platform application. You have to install Floola in your iPod before you use that application.
Once you have installed that application in your iPod you can use that application to transfer any video and music to your iPod provided that your iPod can play it. Since it is cross platform, you can have both the Mac and Windows version of the program in your iPod so that you can use any version depending on the computer from which you want to copy the music and video.