yes. Only way it will change is if the truck is turned off and turned back on. Sometimes you will hear it good after it has been running. Wife drove it the other day and when she pulled into the driveway, it was making that noise as it was coming to a stop then of course put it in park and it was still doing it.

 

could be a bent flex plate

 

I went to my local mechanic that is not a chevy dealer. He has worked on tons of the 5.3's. He says 110 percent a collapsed lifter. Chevy dealer called me today and said they have gone out and started it all day trying to duplicate it and said they can't. Going to keep it one more day and see if it does. They hear it clear as day in my video and are really concerned but cannot get it to duplicate so if no duplication then no repair.
I don't know if a periodic collapsed lifter damages the motor or not.