You should only see the ad once on YouTube. We do apologize for this. Did you try clearing your cache?
Nice potential-customer-service btw. Thanks! Although I did rather imagine you lot would be all over this thread :-)
Just to show you how much it shows up: my WIFE already recognizes it, just from hearing it when I'm working by her side.
I'm sure retargeting works in some context, but I'm guessing you are overdoing it in some cases. (I'm in Brazil, but I browse mostly in English. Maybe it makes me a particular case?).
Probably the #1 cause for people to install ad-blockers.