As you can see, though not completely perfect, these pics give an idea what you can do. And the video (unfortunately crashes most of the time) feature, is great. You gotta practice so to not warp and distort the “face” as you talk but it can be used for lots of pranks and fun times! And it’s FREE!!!!!!
So there’s this app (named above) that does live face replacement. And you can take a photo if the result or a video. And it tracks the “mask” with your face. It isn’t perfect and needs work but the results are pretty awesome.