Whether or not it drains me depends on what type of videos I watch. There's a big difference between a vlog from a rockstar vs a paradox riddle. Whether or not the video is accompanied by a voice and face makes very little difference to me, it's more about the kind of thought the video provokes.
As for whether or not Youtube is introverted or extroverted (or ambiverted)... I'm not sure. Firstly, what do you mean by "introverted, extroverted, or ambiverted"? Unfortunately, those are ambiguous terms of ambiguous concepts, if I'm to be of any help, I'll need you to be more specific
I mean, my first thought is to be a smart aleck and take the terms too literally as it relates to "energy" and "Youtube", in which case I'd say something like "Youtube is not a human personality"

The next thought to cross my mind is that the act of indulging in Youtube videos is usually introverted, regardless of the content, considering my understanding of the term suggest that "introversion" is a matter of stimulation from within oneself. In which case, Youtube is more often an activity done alone for the stimulation that is your personal impression of the work on Youtube, much like reading a book, listening to music, or viewing art. The fact that some of the videos have social themes makes it no less introverted, much like a book on social affairs isn't all of a sudden more extroverted than other books. I think most entertainment is mostly an introverted process, despite being significantly extroverted as well, but the way in which extroverts use the entertainment might be different, buuuuttt....
I don't know what I'm talking about and I'm getting bored
