There is simpler explanation. People who watched this video acvtualy buy the product more often then people who didn't.
So it flaged you as someone potentially interested and selected you when advertisers chose to target people similar to their actuall historical clients.
(I'm not saying they don't scan videos. I'm saying they don't have to do it to achieve effect like this)
Proton Pass has a feature exactly for that. You can create unlimited number of aliases, and kill ones that bacame compromised.