I think your question depends on the audience. I mean if you're watching FilthyFrank, you're going to be expecting some sexual humor (especially if you're subscribed to him), and this case sex is "okay." However, if you're watching Numberphile and sex topics come about, then it's a sensitive topic because people are looking for math related videos, not sex. Therefore, get to know your audience if you're wondering what's okay or not okay. For example, I uploaded a video about my laptop breaking, and I cussed a lot in that video. Then a day or two later I got a lot of dislikes. I know the cussing was the issue because my video was structured the same way as my other videos but with a lot more cussing. Now I know that my audience is sensitive to curse words. Another way you can determine what is a "touchy" subject is by looking at your demographics and determine what age group you're targeting.