Kinda makes a person wonder what subjectively unacceptable activity you're into... Especially considering that, statistically, users of the legal drugs alcohol and tobacco kill exponentially more "innocent" people, than users of all other drugs combined.
That's not an argument in favor of legalizing drugs, but an argument for restricting the access of tobacco and alcohol. Such as only selling it to adults, in bars, outlawing attempts to market it to children and so on.
And if that plugin gets popular enough, they will request it to be taken down too! Google aren't stupid -- they are perfectly capable of protecting their content if their lawyers want it. For example, it is basically impossible to automate search queries because Google really hates it when you using their search engine but are not exposed to their sponsored results. They have very sophisticated means of determining when it is likey that a user is a bot and will then serve up an annoying captcha. They will do the same thing with youtube. The difference is that, while search engine results are "theirs" and copying them can be seen as plagiarizing, taking the audio of youtube videos cannot because the videos aren't Googles property, they are owned by the youtubers who created them.
According to the law it is probably alright for them to do what the hell they want with the content users uploads, but from a moral standpoint I think what they are doing is highly unethical. Google has gained enormously on everyone who uploads videos, whether it is original stuff, remixes of other material or dvd rips of popular tv shows. I think they should return the kindness and allow as unrestricted usage of the content on youtube as possible.
"Don't drop acid, take it pass-fail!" -- Bryan Michael Wendt