Modified video or create animation

we have a video already in youtube that how the app works but we add one more function to the app and that needs to be modified with better animation, we are trying to use stocks with real people that can simulate the communications from one side to other side like phone call. This is a mobile app live time translation, so it needs to be simulation of people talking from country/country or from one person/other person this video will be our app advertising and presentation to users. This video will be the official for explain to users how to use this mobile app. actual video is this; [login to view URL] Like the video can be showing in the presentation as half/half screen so we can see one person in one side and the other person in the other side, and showing how it works by simulation with people or animation with people we need something more professional that actually shows and focus how the apps works with the new screens that we are adding which is a new function thats all.