It worked for me.
I right clicked the photo chose "view all sizes-> original"
From there I right clicked and chose "view image". View image might be called something different based on your browser. I'm using firefox.
Now the image should be on the page all by itself. I copied the url and pasted it into the add image tool
Mine link was http://farm3.staticflickr.com/2408/1792554131_6696f5629d_o.jpg
Note: linking like this might be against the terms of service but if they close my account i don't really care.
See the "Where is the HTML code and photo file link?" section on flicker for the method they want you to use.