Here's how to do it from DVDs:
First of all, make sure your computer has a DVD drive. If it doesn't, you won't be able to do this. It seems obvious but it's amazing how often it gets overlooked.
If you do have a DVD drive, you will be able to import onto your computer. However, you will need a converter program in order to make it playable on your iPod, since the iPod format is different and DVDs have copy protection format on them.
A good converter to use is DVDfab platinum. Click the link below in order to go to the site, where you can download the trial version. It has worked for me very well, and contains no viruses. The trial version is exactly the same as the full version but limited to a 30-day period.
In order to be able to use the trial version for more than 30 days, you will need a program such as date cracker, which I have also provided a link for.
Download and install both programs, then open date cracker. Click “add”, and enter in whatever you want to call the program. Browse on your computer for the DVDfab program, and then tell it to run the program on date cracker. Follow the instructions given.
Then run the program through date cracker. Remember to always open it using date cracker, or else it will stop working if 30 days have already gone by.
Put the DVD into the computer, then select iPod format on DVDfab. Change the destination to wherever you want your movie saved, and start the process. This will take a very long time since movie files are huge, so be patient. Once it’s done, put the movie from wherever you saved it into iTunes and from there onto your iPod.
For any movie files already on your computer, just drag into iTunes. If they are the wrong file type (iPods accept MPEG-4 movie files only), you can use DVDfab to convert those too. Just change the source location in the program.
And here's how to do it from places like Youtube:
I have been searching the internet for quite some time now looking for various video converters and downloaders. So far the best one that I have found is called KeepVid. What is really nice about this is that the only thing you download is the video itself. And it's really easy to use.
Just copy the YouTube video link and paste it in the box on KeepVid. Click download, and it'll give you two options, which should be:
›› Download ‹‹ (.flv - Low Quality)
›› Download ‹‹ (.mp4 - High Quality)
Click on the MP4 one, and save it to your computer. Then drag the saved file into iTunes and sync your iPod.
Just one thing to note, however. Sometimes when you click to download the video, you'll get a document with strange characters instead of the save box. This is fine and will not stop you from downloading the video. All you have to do is RIGHT-CLICK on the link instead, and select "Save target as". Then change the filetype to "All files" and type .mp4 at the end of the filename before downloading.
http://www.keepvid.com