WASHINGTON — Thirty years after failing to convince the U.S. Supreme Court of the threat posed by home video recordings, big media companies are back and now trying to rein in another technological innovation they say threatens their financial well-being. The battle has moved out of viewers’ living rooms, where Americans once marveled at their ability to pop a cassette into a recorder and capture their favorite programs or the sporting event they wouldn’t be home to see. Now the entertainment …