It's been some time since Solange Knowles has put new music out, but last night she debuted a song called "Losing You," a vibrant pop track which she wrote with Dev Hynes (Blood Orange, Lightspeed Champion). The song's accompanying video finds Beyoncé's younger sis strutting in Cape Town. Melina Matsoukas directs. [videoembed size="full_width" alignment="center"][/videoembed] The single and its B-side "Sleep ...