Then you're a thief.
You agreed to watch the advertising on Youtube in exchange for the content being provided. If you block that then you are breaking your part of the agreement. You want to go someplace else, fine; but that does not entitle you to view the original content. If it was ripped and uploaded somewhere else, you're still a thief.
We're not talking about the MPAA here. They don't generally upload their stuff on Youtube for the pittance of adrevenue.
People like The Angry Videogame Nerd , TotalBuscuit, Yogscast, Northenlion, they are the ones who will be affected. Why should they continue to make content for you to watch, if you're not going to watch the ads which is how they support themselves? They'll just stop and you wont have any new content to watch from them.