The problem is the realism aspect. Look at how often comedic intent is misinterpreted both on the internet and real life. You could end up causing real damage to a person's reputation through this, especially if the video clips are taken out of context which is something that frequently happens already.

Direct observation is the best tool we've got as humans for determining the truth. We augment with tools, but even reading the output of those tools is done with our eyes. We need to be able to trust what we're seeing.