For animations video games use motion capture already, and an interesting thing is that you cannot ask your mocap actor to act normally and expect the result to look good, for some reason natural motion is not desired in games and studios both ask the actor to play in a very specific way, and then animation artists still have lots of work tweaking the animations so that it looks good.

It's the same reason why acting on a theater scene doesn't just requires that you project yourself in the role and try embody the character but also adapt your motion and expressions so they can be understood by the public sitting afar.