This makes no sense to me at all... you have a video of the other person open, but then you mute the audio and have to type everything out? Why?! Why would you

This makes no sense to me at all... you have a video of the other person open, but then you mute the audio and have to type everything out? Why?! Why would you just not... talk aloud? Of course, this probably means it's going to be a crazy hit.