Thumbnail size for external images

Hi,
On one of my WordPress websites I often embed large images – infographics, howto instructions etc… from external websites like Pinterest, Amazon S3 etc… here are couple examples:
http://www.buzzblender.com/the-definitive-guide-to-homemade-hummus/
http://www.buzzblender.com/avocado-hummus/
http://www.buzzblender.com/braided-nutella-bread-inspired-by-charm/
So when “Auto Post Thumbnail” generates thumbnails or I manually generate thumbnails for posts with external images plugin add large images to media library to use as thumbnails like 736 × 1103 http://screencast.com/t/6YeAJqNm I am not using such large images to display thumbnails in my theme – max is 180*180 pixels, in fact I don’t need those large images, all I need is small version – 200*200 pixels max to be saved in my media library. Is there a way to set thumbnail size for external images?
P.S In my media settings I have thumbnail size set to 75*75 http://screencast.com/t/Jtewt3A4ZyF0

http://wordpress.org/plugins/auto-post-thumbnail/