That could be an exhaust leak. Best thing to do is let the engine cool completely. Then start it and run your hand around the manifolds and see if you can feel air. If you do it's an exhaust leak. Or you can use soapy water and watch for bubbles. They also could be the famous Hemi tick

 

 

I believe I counted two missing exhaust manifold bolts in your video. Broken bolts thus exhaust leak. Funny thing is your noise doesnt sound like an exhaust leak to me. More like valve train noise. Might just be sound of video tho....

 

In your short video, I see at least two exhaust manifold bolts that are sheared off. That is your tick. Leaking exhaust manifold. There are many many many posts and threads about broken exhaust manifold bolts on the hemi. Some searches, some reading, some youtube videos, and you will soon have a plan to get your tick sorted out.
What you have there in the video is definitely exhaust manifold leak tick.

PS: The other "hemi-tick"s mentioned are on a well tuned perfectly running hemi and you are under the hood and hear ticking. Those ticks are the fuel injectors firing. Completely different and completely normal.