My Cloud Twonky and custom thumbnails

I currently have a My Cloud and Twonky likes to create thumbnails for my videos files.  Is there a away to create custom thumbnails?

Yes, just put a jpg file that matches the movie name in the same folder.

My Movie.avi
My Movie.jpg

Thanks I appreciate it, worked like a charm.  Now if only I could get a scrapper to work with it like with XBMC but you can’t have it all.