What copyrighted work is the most likely to be taken off of Youtube?

In one of my classes, we’re doing a project on ethics, and my group chose to explore both sides of internet ethics- more importantly, copyright infringement on the internet (we’re looking at SOPA, PIPA, ACTA, megauploads and Kim Dotcom, as well as Pinterest, because many of our classmates are members. If you can think of anything else we should look into, that would also be appreciated).

As a sort of social experiment, we want to purposely post copyrighted material on Youtube and see how long it takes for them to take it down. We’d record each step of the process to include in our presentation and hopefully we won’t get sued or anything like that (with as many videos that are posted daily to Youtube though, the chances of that happening are slim)!

So I was wondering if there was a song or TV show clip that we could post and would have a high likelihood of being taken down. If your suggestions could be backed by evidence (many videos of this kind have already been removed, this company is very strict about its copyright, etc), that would be even better!

Any ideas?