The images were thought invoking, but had they been subliminal you’d not be discussing them, having not consciously seen them. Here’s the book that started it all ...
https://www.amazon.com/Hidden-Persuaders-Vance-Packard/dp/097884310X
Correct & Vance Packard was good early researcher in this area too. I was referring to running the video at .25 speed and then you can see the images flashed therein - for example there are two or more times a very sexually explicit photo is presented with “Subscribe” on the pic. There are also pics therein embedded which look to be a mess of dots but you can tell there are patterns embedded therein too.