Do not want to see youtube adverts for 5 secs?
Just write a letter to the advertiser like: " Dear xxx, thank you for your product advert on youtube, but I'm not interested in. Regards".
I think it is absolutely useless if some people writes this kind of "thank you", but what if those some people counts more thousands or hundred thousands?

Chowhound
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GameFAQs
GameSpot
Giant Bomb
TechRepublic