> So it turns out the “YouTube voice” is just a variety of ways of emphasizing words, none of which are actually exclusive to YouTube—people employ these devices in speech all the time. But they generally do it to grab the listener’s attention, and when you’re just talking to a camera without much action, it takes a little more to get, and keep, that attention. All the videos I used as examples in this article come from popular YouTube accounts, with hundreds of thousands or millions of subscribers—in other words, from people who know how to engage an audience.
There are other factors at play here, too. YouTubers’ monologues often speed up and slow down, for example. “Changing of pacing—that gets your attention,” Baron says. And elongating certain words helps change up the pace. People also tend to move their heads and hands a lot in these videos, raise their eyebrows, and open their mouths wider than necessary. (Link)