I just want to say, it has been done before. In 1985 (Live Aid) and in 2005 (Live8). This is much of the same, except for the short films between the concerts (actually between every song). At first it's OK, but when you have seen them five times, with Madonnas Hey You (think that is the name of the song) between every damn film. After watching 15 hours, I was starting to get brainwashed. But the music was great and the show was coll, so it was worth it.
My favorite performances was Wolfmother, Roger Waters, Foo Fighters and Spinal Tap. Their second song had around 20 bass players. It was awsome!