This might have been posted before, but. . .

I've been uploading videos to my site and the thumbnails are not showing up. Is there a fix/plugin for this? It'd be nice if my visitors could see what they're clicking on. Thanks.

Here's an example of what I mean: http://www.jcjunkie.com/photography/videos/

P.S. I'm using the latest zen photo (1.4.0.4)

Yes, it has been discussed before lots of times what you would have found using the search. Also it is explained on the troubleshooting on the user guide.