YOU HAVE AN AMAZING OPPORTUNITY, HERE.
Seriously.
You control the backend of a service being used by pedophiles, and you are working co-operatively with law enforcement.
Proceed with this the right way, and you could very well end up helping to stop some specific instances of child abuse, get kids out of those situations, and get some sickos put behind bars.
/u/nywald - The Next Chris Hansen
That's a way more noble and gratifying cause than a SnapChat knockoff. And financially... I don't know the in's and out's of it, but there has to be some sort of grant and/or bounties to be claimed on an effective system like that.
If you ever plan on just giving up on it - I would more than gladly take it over and pursue that route.
Though if you just want them gone...
Here's what I'm thinking:
Overlay when a visitor first comes to the site. Explain that the site is in Beta mode, and only available to select markets. Please enable location data to proceed.
Hit up the browser for geolocation data. The visitor should get a popup similar to "This site would like to access your location. Allow/Deny"
If location = USA/CAN/UK/AUS, drop the overlay. Else, re-direct elsewhere.
Cache that info. Normal users should only see it once. Proxy and incognito users should see it every fucking page load.
List city/state/country of the uploader, and all of the viewers.
My theory behind that approach is that it is a minimal bother to normal users (one mouse click). However, it should hopefully freak out users who were intending on uploading illegal material, and hopefully kick out spammers from China, India, etc.
Of course, there are still easy ways for people to circumvent that. Chrome Dev Tools has built-in geo spoofing. My assumption is that any technically competent sharers of illegal content already have better systems in place, and wouldn't use your site.