Thanksgiving has become a day of the year when friends and family get together in the late afternoon, watch the network telecast of the NFL game, then sit down together for dinner -- and turn their television sets off. Thursday was no exception. The overrun of the New Orleans Saints-Dallas Cowboys game on Fox at 8 00 p.m. averaged 15.16 million viewers -- but as soon as it was over, the network's ratings collapsed -- with just 5.7 million tuning in for the beginning of The Simpsons Movie at 8 30 p.m. But that figure was outstanding compared with ratings for some of the other programs airing on Thanksgiving night, including the ABC special, Beyoncé's I Am World Tour , which attracted 3.97 million viewers at 9 00 p.m, and NBC's The Apprentice , which drew 3.37 million at 10 00 p.m.