Proof to why you should test GDI injectors at LOW PRESSURE

Here is a little lesson on why you always test GDI injectors at LOW PRESSURE:
Clip 1:
This video shows you the spray distribution that should have 6 jets but only has 5. See also photo of orifice plate that is at the end of the injector showing 6 holes.
The second injector shows when rotated that there are 6 jets on this injector.
Please note that at high pressure you cannot rotate the injector.
Clip 2:
This video shows the injector at 5 bar pressure where you can clearly see the 6 jets but when you increase the pressure to 100 bar, you are not able to see anything of the sprays that you can examine.
It is not possible to rotate the injector at 100 bar.
In the interest of safety we do not recommend rotating an injector over 10 bar maximum!

[@EXOVCDS]

The noise at 0:48 , can you explain it? Is that the injector vibrating / passing air or something like that? I was listening to a VW VR6 GDI engine that sounded like it had a squeaky belt... when revving the engine and allowing it to return to idle, the noise would momentarily be gone (I assume due to fuel shut off). Removing the drive belt confirmed that it was not a belt related noise. Thanks for any insight you might have!