Is there a setting used in swftools that will fill in the image for the default image or playlists?

Is there a default setting used in swftools that will fill in the image for the default image or playlists?

The playlist automatically generated when a flash file is played using the is empty.

Is there a setting that will get the playlist generator to add the name of an image file with an appropriate extension such as filename.thumb.jpg is I play a file named filename.mpg?