i played varsity baseball and D1 in college. showering after practices/games was second nature. i think the OP video is a bit outside of the norm unless you're a wrestler. a) i think wrestlers are a bit off anyways, but there is a lot of nudity around weigh-ins. wrestlers want to weigh as little as possible during the weigh-in so that they can be put into a lesser weight category for an upcoming meet. that way, when it actually comes time to wrestle a few weeks later, they can bulk up, eat, etc. and actually weight MORE than they did when they originally weighed in.
i think nowadays weigh-ins are a bit more "closed door" than they were back then. i don't wrestle and have never wrestled, but i knew a couple of them.
for other sports (mine included), showering was no big deal. if anything, we used it as a time to goof off, give each other shit, talk shit about the opposing team, talk about pussy, etc. nothing weird ever happened, despite what the gay pornos may tell you.
now a frat house, that's a different story... haha