The FKKs have been very careful with the usage of cameras so there is unlikely to be any decent footage. Not only club security, but all of the girls and many of the club guests are very vigilant in stopping any form of hidden photography.
Of the clubs I knew well, Artemis Berlin, Palace and Sharks in Frankfurt and Globe Zurich have very strict bans in place. Oase permitted the use of mobiles for a while but were very vigilant in watching out for anyone taking pictures or video. I was there once when an American was spotted by one of the girls. She called security who smashed his phone in front of him (and many of the girls and guests) and threw him out unceremoniously. He also received a lifetime ban, I was led to believe.
At Goldentime near Duesseldorf, for a long time it was possible to use your mobile publicly and I know that some surreptitious photos of the girls were taken by guests as a Belgian guy once showed me a couple of shots he had managed to sneak of one of my favourites in the garden. Wish I had been able to keep them for memory's sake! GT then clamped down and you had to declare your phone on entering the club. They then put a sticker over both cameras. Anybody seen using a phone without stickers had it confiscated immediately and they were thrown out.
A story also circulated in the club that a Chinese guy was once found trying to film when in the room using Google glasses. His girl noticed, made some excuse to leave the room briefly, called security and they took the glasses and destroyed them in front of him. Possibly apocryphal but a salutary warning given the cost of google glasses at the time!
Do any videos exist? Almost certainly because, even with the security mentioned above, it was always possible to snatch a quick glimpse of what is going on. Publicly available? Unlikely, but I like the OP, would love to be proved wrong.