I've just been skimming through the huuuge discussions between the pilot himself and the big cheeses on fpvhub, the FPV UK (model flying association) forum, and from what I can tell he was flying it LOS, no Vtx, across the water from an existing R/C club site. He lost control fairly early on, but hadn't configured the failsafe to do anything sensible, so it held its heading and flew up the river to the BAES submarine shipwrights. If he'd been aware of the relevant rules, no fly zones and authorities, he'd probably have informed the authorities and it'd have been fine.
As it was, the airframe was recovered by a BAES employee and handed over to the police, who got from the images of the man and his vehicle from the beginning of the recorded video (and his labels on the airframe) who he was and where he lived. No YouTubing involved.
Having got into trouble, the BMFA (British AMA equivalent) were unwilling to help him out as he was using a UHF control system and he himself failed to get any legal advice before his hearing. He's gotten some advice (and plenty of flak) from FPV UK, and he's now in contact with Trappy.
FPV UK have been working with the CAA for quite a while and gotten FPV'ers some pretty good deals in the regulations, hopefully this isn't going to put them back too far.