It would be vast overkill to download a whole video just to present a thumbnail, and the user experience in the delay while the whole file is downloaded and processed would render the feature fairly useless.
Which leaves the question of why Facebook would do this open... It might just be really bad practice and an under-/non-optimized crawler.
Wouldn't help you with new material, of course.
http://petapixel.com/2012/11/25/facebook-removes-risque-phot...
Automatic detection of child pornography - http://ro.ecu.edu.au/adf/60/
our approach can achieve a prioritization of
content (equal error 11 – 24%) to improve the
efficiency of forensic investigations of child
sexual abuse
It's good to prevent the re-sharing of child pornography, but a lot of companies don't like to talk about the systems because they're very much the same systems that the same companies are busy telling the content industry that they can't build to enforce copyrights. So they're generally kept pretty hush-hush by a kind of gentleman's agreement.
I think general copyright is actually a thornier problem and this secrecy is unnecessary. CP is just something you can block if you see it. Tracking down exactly which uses of a copyrighted work are intended to be allowed and which are not is really much harder. And I think that's a legitimate argument, especially because it recasts the copyright debate in terms of compromises that make sense: if clearing a bunch of rights is confusing, maybe certain types of compulsory licenses are more attractive. But that debate is for another thread...
| I think general copyright is actually a thornier
| problem and this secrecy is unnecessary
2. Even if you detect that a video contains copyrighted material, there is no central registry for you to determine if the person (or entity) has permission to distribute/use that material. Even if there was such a registry, how do you link it to an online id on some random website?
3. There is no middle-ground for fair use. Fair Use is something that is usually only definitively determined after a court battle. If restrictions are too strict, then the only way for one to exercise their Fair Use rights is a court battle. This effectively means that Fair Use would be dead for all but some rich, motivated people (at least on large content networks, e.g. YouTube).
[1] Unless it wins brownie points with the public for getting a system in place to protect the 'big guys,' who are obviously the only ones that matter.
I was supposed to meet with a Scandinavian vendor a few years ago that provides a service where you can match SHA hashes of files against known illegal content. I recall the pitch deck said that they had millions of records to match against, which I found incredibly depressing.
I ended up bailing on the meeting... it's a subject I don't want to learn more about.
I know they've got lots of money but really, are they wasting bandwidth and memory so badly as to download terrabytes of video they don't need?