Hmmm.. my csv file has the url for the specific photo and thumbnail in flickr and, when I select on the url that I within the csv cell, the correct picture appears.
I see where, in builder, you can place each picture but I already have the latitude/longitude in the csv file to go along with name, description and photo/thumbnail urls. When I open the "inspect element" in chrome I see that the url looks correct to me and, if you copy that and past it in a new browser window, you get the correct image. Guess I'm missing the "download/all sizes" function in Flickr.