Prince’s estate is giving us one small blessing as we approach the two-year anniversary of the Purple One’s death: Never-before-seen footage of the maestro and the Revolution rehearsing “Nothing Compares 2 U” way back in 1984, years before it became popularized by Sinéad O’Connor. He jives. He gyrates. He plays the guitar. He does that cool thing where he pushes the microphone stand away and it bounces back right in front of him. An icon at work.