Interesting. Do you use only creative-commons-licensed material or do the terms of Flickr's "copyright" license actually allow this use?
It seems to me that embedding an image on another site, even with a copyright notice, would be reproducing the image and not allowed under the normal terms of a copyright license.
Sorry to be a party pooper, but just ignoring legal issues around reproducing other people's content (some of whom make a living from selling it) isn't going to make it go away.
Edit: to answer my own question, the images are only Creative Commons attribution-licensed photos. From the 'about' page:
> The photos are pulled from flickr using its search api, searching only creative commons material, and watermarking them with the name of the author, to be in accordance with the creative commons licences, which all require attribution
This isn't my project - I just found the site.
Even though these images aren't meant for live sites, it's good to see that the images have proper attribution.
I tried two quick examples in the browser for a little test. Thinking in terms on banal clipart I use the tag "happy" and I get back a very nicely shot photo of two attractive people making out in a doorway. Hmmm. Then I try "friends" thinking I'll get something a little more office appropriate and I get a nicely cropped image of two young ladies in bikinis frolicking on a beach.
Nothing R rated or tasteless, just not the kind of thing I want to explain to my boss who's looking over my shoulder. Think I'll be sticking with http://placekitten.com/ then...
Interesting... playing around with similar tags and some offsets, I got those results as well as some irrelevant images (aurora borealis for "friend"). Definitely a concern when you need the placeholders to be at least somewhat relevant.
Personally, I have no problem with using http://placehold.it/
It seems to me that embedding an image on another site, even with a copyright notice, would be reproducing the image and not allowed under the normal terms of a copyright license.
Sorry to be a party pooper, but just ignoring legal issues around reproducing other people's content (some of whom make a living from selling it) isn't going to make it go away.
Edit: to answer my own question, the images are only Creative Commons attribution-licensed photos. From the 'about' page:
> The photos are pulled from flickr using its search api, searching only creative commons material, and watermarking them with the name of the author, to be in accordance with the creative commons licences, which all require attribution