Do you want to make thumbnails without having to download any extra software? In this video tutorial I will teach you how to make YouTube thumbnails using the Pixlr Online Editor. The Pixlr Editor is a web based application. It should work on most browsers that support the Adobe Flash plugin.
However I recommend using Mozilla Firefox for the smoothest experience.
There is no text version for this tutorial. Watch the video above, or check out this GIMP tutorial for YouTube thumbnails.