Youtube don't check humanly the ads. So they used this filter to pass the verification. You can report it if you think it's not ok. They will take measures. Also don't forget that the ads are based on your activity. Maybe is not a mistake.
Sometimes ads are based on your history or most search so if you're some kind of naughty bastard on the internet then expect more of this unless you personalize your ads on your google account. That's just my guess mate.
Youtube knows you're a horny wanker from your browsing habit, thus the ad
Internet adds don't work that way. You can indirectly influence what adds you see. And you definetly watch too much porn :p