I'm not a large scale ML person, and not intending to take away from the achievement of the team in the OP, but experiments in large scale, unsupervised learning have been going for a long time (even using the autoencoder approach). When you think about it, large scale requires unsupervised...

Here is an old example with hundreds of millions of records and instances:

http://aaaipress.org/Papers/KDD/1998/KDD98-028.pdf

Both authors are now with Google.

Also, people here may not be as up to speed on the state of the art in face rec as they think they are. It's not as much of an unsolved problem as it was even 10 years ago.