Warning Thumbnails file nname cannot be empty

Hi,

I added a portfolio item with a youtube url in the media link. I went to view it, nothing shows up. I look at backend portfolio items under thumbnail I get:

Warning: copy() [function.copy]: Filename cannot be empty in /home/skeeter/public_html/wp-content/plugins/nimble-portfolio/includes/class.NimblePortfolioItem.php on line 161

https://www.ads-software.com/plugins/nimble-portfolio/