Thumbnail support for video clips ?

Has anyone suggested/implemented generating thumbnails for video clips ?

In my case I have a number of avi files where it would be great if when the avi file is uploaded the first frame from the avi could be extracted and used as the thumbnail.

Is this possible as surely I am not the only one who has short video clips taken with a digicam that sometimes show more than a well taken image ie. childs first steps etc. ?

Iain