Maybe the site can keep a log of who and what gets uploaded and how many are uploaded.
Then that could help out in finding if they are doing the same thing again. Some many take away there uploads and then just upload them again to push them to the top so more see them and click on them. I have seen this a couple times but seems like now after the CGShare site stared being used your seeing this happening more. 
I can see upload taken away and put back up if it is to change the download site but can't you just edit your upload to change the download link.