MovieMator Free Mac Video Editor is a free video editor that has the most basic editing functions. However, it you have downloaded videos and they do not work on your computer, then you may be able to re-publish them with this tool. For example, you could de-interlace the movie to see if it now works on your device or to see if it works on your screen without becoming blocky and/or having grey lines. You can snip, rotate and edit the movie, and you can edit the properties of movies with this program.