If your video files are not the proper format, you won't be able to add them to your itunes library. Check your video's format before proceeding.
[header] How to add personal movies to itunes [title] Check the format of the movie file you want to add. [step] Itunes only supports the mp4 (m4v) and mov formats. It does not support many popular formats, including avi, mkv, and wmv.