The thumbnail is a picture that illustrates the video when it is not played. Libcast generates a thumbnail for each video, but you can easily customize it.
To change your thumbnail, you have to go on My Documents, hover over the video and hit "Modify" in the contextual menu. Then, on "Thumbnail".
To change it, you just have to click on the most appropriate picture. Libcast generates 12 pictures but if none of the suggested picture fit your needs, you can download a picture from your computer.
When you have choosen the right thumbnail, you just have to press 'Save'.
Good to know
The picture have to be in PDF, GIF or PNG format.