What will it take to make music streaming profitable?

Music streaming is being seen by many as the way ahead for the music industry. Last year, music lovers around the world streamed 146 billion songs on their computers, tablets and smartphones. That's double the amount streamed the year before. But despite the speed at which this industry is growing, few music streaming companies are yet making money out of it. Last weekend, the American telecoms giant AT&T decided to quit the business. Sony will soon be following them. So what will it take to make music streaming profitable? The BBC's Katie Hile went to investigate.