“Be brave. Be brave. Be brave.” So says the awesomely named Benedict Cumberbatch toward the end of the newest trailer for ‘War Horse,’ a bit of marketing seemingly engineered to produce moist eyes and Oscar nominations. Steven Spielberg! World War I! Lush cinematography! John Williams-like music! Horses! In danger! The brave thing would be watching this at your cubicle, since you’ll likely start bawling before its over. Watch ahead.