8 P.M. (HGTV) HOLIDAY BATTLE ON THE BLOCK Lights by the tens of thousands. Soldiers. Dancing snowflakes and a sugarplum fairy. In the third of four episodes, three neighboring families in Youngstown, N.Y., pull out the stops and then some to create the best holiday displays. Kim Myles, the show’s host, offers each $5,000 and some free design advice. At 8:30 the competition concludes in Markham, Ontario, with a crèche of live animals, a re-creation of Santa’s workshop and a Christmas sound-and-light extravaganza.
8 P.M. (TNT) CHRISTMAS IN WASHINGTON 2010 Ellen DeGeneres hosts this annual concert benefiting the Children’s National Medical Center, where the president and first lady will hear performances by Mariah Carey, Annie Lennox, Maxwell, Miranda Cosgrove, Matthew Morrison and Andrea Bocelli.
8 P.M. (WCBS) YES, VIRGINIA After a playground bully makes fun of her belief in Santa Claus, Virginia O’Hanlon, 8, left, heads into the streets of New York with her friend Ollie to search for the truth. Her quest inspires her to write a letter to The New York Sun, where, after a little persuasion, the newspaper’s editor, Francis P. Church, responds, “Yes, Virginia, there is a Santa Claus,” in what was to become one of the most famous newspaper editorials ever written. This animated tale, featuring the voices of Beatrice Miller, Jennifer Love Hewitt, Neil Patrick Harris and Alfred Molina, is inspired by the holiday story from 1897.
8:30 P.M. (WNET 13) NEED TO KNOW Jon Meacham offers his thoughts on Richard C. Holbrooke, the special representative for Afghanistan and Pakistan, who died on Monday. And nine thinkers — including the writers Gary Shteyngart and Reihan Salam, and Anna Lappé of the Small Planet Institute, a grass-roots organization that addresses hunger and poverty issues — each name one thing they would do to counter problems in the United States.
9 P.M. (WNBC) DATELINE NBC Natalie Morales reveals details behind the case of Elizabeth Smart, who in 2002, when she was 14, was abducted from her upper-middle-class home in Salt Lake City and held for nine months. On Dec. 10 Brian D. Mitchell, an itinerant street preacher, was convicted of the abduction. He is to be sentenced on May 25.
9 P.M. (BBC America) LAW & ORDER: UK When a teenager is murdered, Crown Prosecutors James Steel (Ben Daniels) and Alesha Phillips (Freema Agyeman) struggle to keep their promise to bring the person responsible to justice.
9 P.M. (VH1) VH1’S TOP 40 VIDEOS OF 2010 Industry insiders, pop-culture experts and the artists themselves — among them, Eminem, Taylor Swift, Katy Perry, Usher, Maroon 5, Kings of Leon and Lady Gaga — talk about the year’s most memorable music videos in this two-hour special.
9 P.M. (TLC) WHAT NOT TO WEAR Sarah, a 26-year-old athletic trainer with brains, beauty and a promising future, crosses the finish line last when it comes to her attire. Her cynical, self-defeating attitude doesn’t help. Stacy London and Clinton Kelly try to coach her into the winner’s circle.