With video you can pause and compare images, but likely some would argue that static image and video aren't the same thing as with video you have different specs such as response time, ms for black to white, 'ghosting' and I don't know what else... But in the end, A/B comparison is still error prone tests where placebo can influence the result... It all comes back to BT and DBT... A/B comparisons are inherently unreliable.
It's not rocket science really... With 2 people, connect 2 power cables to outlet, and just switch with testee having to identify... If it makes a significant difference, should be easy, if not, then likely not worth the $ in case of obscenely priced snake-oil cables! Reasonable people who care about reality/truth will be convinced after failing such a test. Those who can't let go of their irrational beliefs won't, but...
The sad thing is that so few audiofools are even willing to test their beliefs... But hey, 3/4 of Americans believe in angels, 1/3 believe in UFOs, 1/4 believe in homeopathy, 1/4 believe in astrology, 1/x believe in audiofool snake-oil, etc.
People who want to believe will believe in anything... And worse, no amount of proof, evidence and arguments will convince those who do not want to be convinced...