By Wes Parnell From New York Daily News NEW YORK—Police released video Sunday showing a gunman opening fire on a Queens family barbecue, fatally striking a 10-year-old boy. The shooter pulled up in a dark SUV to the home on Beach 45th Street near Beach Channel Drive in the Edgemere section of the Rockaways just before 9:30 p.m. Saturday, the video shows. He got out of the vehicle and fired eight rounds into the home, the video shows. One of them struck Justin Wallace, who was looking forward to celebrating his 11th birthday Tuesday. The spray of bullets also hit Justin’s 29-year-old cousin, who was hosting the barbecue. Justin was rushed to St. John’s Episcopal Hospital but he couldn’t be saved. His cousin was taken to Jamaica Hospital where he is expected to survive. “This [will] tarnish my life for the rest of my life,” said the slain boy’s father, …