Sounds like a heat shield rattling around. Have you tried putting a gloved hand on the heat shields to see it that would stop it. Some times you have to just grab and hold a few things to eliminate the "outside" items that can rattle. Once the outside is eliminated, then you can think inside noises....

Have you tried putting a stethoscope on it?

Narrowing it down to left/right etc helps as the video is not clear

 

I’ll see what I can do as far as eliminating anything external. If that doesn’t help I’m planning on picking up a mechanic’s stethoscope at some point this weekend

I appreciate the reply man.

 

mighty metallic. id think heat shield as well. check the full length of the exhaust system

 

After checking that the heat shields are tight front to back, I'd check that the headers are still firmly attached to the engine. Those nuts can back off the studs causing the flange to start banging on the exhaust port or the studs. I would think it would be louder than in your video, but it can be hard to tell in a video.