well, to answer your question from measurement alone I definitely think the G4 is better than the G3 with the waveguide added and DSP, resulting in much better FR.Because in purely comparative terms it suggests relative differences in FR.
But I have to say the youtube is completely useless piece of information, in such case your problems I can immediatly come to mind are:
1) you are supposed to be using something worse than the target purchase, which in itself severely coloured the sound already, e.g. if you have a bright speaker/headphone, you would prefer a way too dark monitor in this case and vice versa
2) from the quick view of the video they don't even use repetitive sections of the track to make a comparison, that would induce a lot of illusions.
3) from the FR included in the video the room modes are entirely not corrected in the comparison and likely they don't place in the same location during playback, that makes the FR in the video completely different to what you would actually hear in real life.
So personally I would opt from Amirm's anechoic measurements and the type of room mode correction built in to dive into the real purchase (in my case I upgraded from KEF X300A to the Genelec 8030Cs), this works much better than some random youtube comparison