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.
Maybe you're in a library?
It is difficult to summarize video chat or phone call for documentation purpose, that is the only situation I can think of where this can be useful! A bit more than just texting.