yeah that sounds rattly oh right.....
Does it sound like its from underneath the car rather than the engine its self, hard to tell on the video
If so, sounds like it could be a couple of things:
you cat my have crumbled a few bits off, and they are stuck in the cat pipe.
your Turbo / downpipe bolts my be lose causing it to rattle
Best thing to do it jack it up and have listen where is comes from....