Im not quite with you on this one.
Because as you can see, the sound is very stady at 1500 rpm.
And only at 1500 rpm. not above and not under.
And I would expect worn out lifters or blocked to give this sound not only at 1500 rpm then. but also under 1500 rpm then.
The sound is also a bit more heavy duty ratling metal to metal sound that I have experienced with worn out or bloked lifters.

My best guess is that the chain are worn out and thenb strethed to the point were the timing has changed so much, so the valves are hitting the pistons.
This would might give sence because exactly at 1500 Rpms. the cam adjuster changed to the advanced setting og the inlet cam.
But then why is then going away already above 1600 rpm where the cam are still in the advanced setting all the way up to around 4500 rpm.

And most likely lifters are beginning to drop oil presure with a hot engine oil not cold.
So it would be the other way around with hydraulic lifters or am I wrong?

Im a litle lost in this problem.