@flozen It's disappointing when something is labeled "voyeur" or "hidden," and the subject clearly knows he's being recorded--sometimes holding the camera himself. A guy wanking in a locker room mirror might look "risky," although if he's a trainer at the gym and the place is closed, there's no risk.
The three films you mention were indeed hidden camera material, part of the "Straight Off the Mat" series, showing weigh-ins and showering at university wrestling matches somewhere in the US. I did some searching on those a while back, and needless to say it caused some reaction among that community. I seem to recall that university names were blurred out, but I'm not sure. (There was similar reaction to the "Allen Snaps" still photos taken at California swimming and water polo matches. While those didn't show nudity, they featured bulging speedos, some worn by pre-18 guys.)
There remains, though, the issue of privacy and its potential violation thereof. In most jurisdictions, photographing someone is a violation of privacy only if the person photographed "has a legitimate expectation of privacy." In real hidden camera material, the subjects have not, by definition, given consent to being photographed. But to what extent does someone on a public nude beach, or in a communal locker room/shower, have a "legitimate expectation of privacy?" He is giving de facto consent to those around him to see him nude, but does that consent extend to people watching a video? I haven't researched the case law on this; if someone has, please provide input.
This is entirely different than the growing number of "over the stall wall" phone videos of lads wanking in the toilet. These guys do not want to be seen by anyone and clearly have an "expectation of privacy."
And, finally, there's the issue of age: Much hidden camera material has younger men as subjects, and while it's nearly impossible to determine a guy's age by looking at him, there's no guarantee that this anonymous person is 18+, which is the marker for "child pornography" in most places. University students are usually 18+, but I've seen some toilet wank videos where the subject was most likely younger. That's not something I want on my computer...or on this site.
A final technical note: I'm baffled by the quality issues of some older VHS-to-digital conversions. There's a lot of cheap and effective software available than can correct brightness, contrast, and saturation. I don't know why people haven't used that.