What I'm about to suggest is not the answer that you are looking for, but I think we could use a better methodology and I think you will like a more technical approach.
IIRC your printer is in a makerspace, where you have different kinds of equipment. Maybe you have some some studio equipment that you could use to measure with precision the resonant frequencies. You just need to repeat the same test, giving that the test its good at exciting the resonant frequencies, with a good audio recording equipment, it needs to be good in the low pitches. The recorded noise will be a good estimation of the frequency response of the printer. This is used in CNC machines as a low cost vibration measuring setup, specially to manage chatter.
Using this setup and a sound reference, to calibrate the amplitude and get repetitive (but not accurate) result, you will be able to know the frequency and one estimation of the amplitude of the vibration, so you could measure more effectively the improvement of the vibration response. I know that we are really doing this to improve prints, but a methodological approach could explain some inconsistent results better, and lets be honest, the community is full of inconsistent results.
Of course, ideally this will need to be done with acelerometers, but this setup gives a lot more quantifiable data than the visual one and is still pretty simple. The downside is that the noise produced by the vibration maybe is not high enough, and well that you need to study the data, so its more work. But hey, consistent results usually saves time in the long run.