Here is part of Flea's Post.
When we were asked by the NFL and Bruno to play our song Give It Away at the Super Bowl, it was made clear to us that the vocals would be live, but the bass, drums, and guitar would be pre-recorded. I understand the NFL’s stance on this, given they only have a few minutes to set up the stage, there a zillion things that could go wrong and ruin the sound for the folks watching in the stadium and the t.v. viewers. There was not any room for argument on this, the NFL does not want to risk their show being botched by bad sound, period.
Read the full post here.