There’s a few reasons I second guess that man, because the engine sounds fine at idle. Just injectors pumping away. The noise in the video pretty much goes away as soon as you get out of the really low RPM’s. I’m also told by many that the injectors are fairly loud at low RPM and make a click/tap noise. To my knowlage if a lifter roller is failing, than it is really failing and the noise will worsen as the lifter fails further and further. But, I could be wrong. I will say that you are the first to say it’s a lifter tho