Firstly you need to have your Music or Video file on one of your hard drives (Note: the video must be in .mp4 format).
Next you will need to open iTunes and insert your iPod, give it a minute or so depending on how fast your computer is for the iPod screen to come up. The iPod screen has a picture of your iPod and shows the capacity you have left.
Thirdly go to file, import and find and click on the music file or video file and click open. Next go to the imported file in iTunes and make sure it has a checked box next to it. Now bring up your iPod page on iTunes and you should see a list of tabs (Summary, Music etc.). Click on the music tab and make sure the box is checked saying, “Sync all music” the same will apply with video but instead click on the video tab. Lastly click sync iPod.
Hopefully this has helped you but note you may not be able to put videos on all iPods.