It be inappropriate to city folk, but to those of us who live in the country, animal mating is part of the decor. I can drive down the street and see horses doing things in broad daylight. My kids learned how baby ducks were made pretty early in life because they mate 2x per year and it's not like you can hide it when the male jumps the female from behind.
I do not really think it is inappropriate. It was more of a shock to see it posted.
I think being put off at animals doing what God made them to do is kinda, um, strange. I mean, if one isn't aroused by it, and I would hope one isn't, I don't understand the issue. The fact that people do feel uncomfortable at this shows just how far technology has removed us from the natural world.
I think the word "orgasm" is more shocking than the video.
I just didn't find the video particularly humorous, personally.

Neither did I. I found people's responses to it more amusing (see above):

I liked the opportunity to show knowledge of anatomy of turtles. They don't have vocal cords. I am unsure of the mechanics of turtle copulation, but I imagine it takes some effort, and I know that the structure of the turtle will result in expulsion of air when doing certain things, so the sound is probably just a side effect of his position and movement.
In case people are unhappy with it, I won't post all those news blooper reels which involve animals in the background. I think the reporters response oddly to them. Are they really that surprised?