Someone present for the desert filming leaked a terrible quality video:

http://makingstarwars.net/wp-content/uploads/2015/08/Leaked-footage-of-Star-Wars-Episode-VII-The-Force-Awakens-filming-in-UAE..mp4

I imagine they'll be able to identify him, on account of there being other cameras rolling and his location on the set being obvious. his face being in the video.

Nothing terribly interesting that I noticed, but I'm sure people will look at every frame of it and find something. Probably recorded by the same person that snapped a bunch of photos of extras on that set that leaked last year.

edit: I guess you hear Finn and Rey speaking for the first time. Sort of. Here is my transcription of their dialogue:

"We gotta move!"

"Wjhoald ahlfada"