Video thumbnail plugin with Wave theme (can't find thumbnails)

I guess tittle says it all.
I browsed through topics, tried some of the code replacements, but no luck,
i keep getting message “We didn’t find a video thumbnail for this post. (be sure you have saved changes first)”.
I guess problem is related to theme I am using (Wave) which has option to upload post image for video and uses Tim Thumbs for resizing.