Well, considering that the boys stay um... "calm" dancing with pretty young ladies, I would say their intentions for putting up this dance are genuine. And the camera does not look like it is sneakily taping unknowing participants either. And the people in the background, as Danee mentioned, are evidence this is not staged. So yeah, it is just some naked people dancing like it is the most normal thing in the world.
As for the site that offers it, enature.net redirects to a site called
http://www.russianbare.com/, a video site that sells naked videos. This does merit a "why would someone buy such videos" thought as expressed in Diary of a Teenage Nudist, though that site, unlike some other "nudist" video sellers I have seen, at least does not categorize videos by the sexes of the people featured.
On the video itself, a somewhat repulsive comment:
"what a bunch of fags... those girls deserve real man"
Yeah - as if there is something more straight (among things you can do on a nude beach without getting kicked out) than dance with a girl. And in what way are the people featured - and gay men for that matter, "fake man"?