Now that I'm at a computer, instead of my phone, and I've watched a little bit of the video...
There is absolutely no reason for this guy to line up all the peaks AFTER they are recorded, much less lining them up all the way down to -18dbfs. It is just pointless OCD behavior.
The only time that you have to worry about VU levels is during recording. That is because you want to run all the outboard analog equipment at that level, because that level is where you get the cleanest signal far enough above the noise floor. If you go roo far above that, the signal to noise gets better, but you start adding distortion in the analog chain.
Once everything is recorded and in the DAW, the levels don't really matter. Peak levels only ever matter if they are clipping, otherwise they are irrelevant. Average levels only matter in the analog world
Now, the only exception to this is when you are using plugins that emulate hardware. These plugins can be level sensitive, just like the hardware counterparts, so you would have to feed them with traditional analog-type gain staging.