This is rather awesome, and a strong sign that Apple is committed to upping the pro level of FCPX. These new tools are effectively integrating, while also hugely simplifying, tools you can access in Motion. If you skim to the last 2-3 mins there's a great demo on using the censor mask with this. After the two shot, dog and island egs there's a great eg of adding to mise-en-scene - cool tool for music video especially ... but usable for custom content for websites like tracking a logo!
https://youtu.be/FR4_zYrp8S8