It's pretty early on in the video. For those of you who don't know, Jenna Marbles is an increasingly famous vlogger, who has the 6th highest amount of subscribers on YouTube. Her and PewDiePie have almost reach a level of celebrity from doing YouTube and make a pretty decent chunk of money doing it, which is pretty impressive. She's actually pretty good at what she does.
I can't stress the important of not reading into this too much, but she does refer to diapers as "fun", so who knows, maybe she's into a little diaper play, or at least definitely knows about it.
How Guys Take A Shower - YouTube