but also because the record's been broken a bunch of different times since then, including one last month:

http://en.wikipedia.org/wiki/The_King_of_Kong:_A_Fistful_of_Quarters#World_Record_status_since_the_film.27s_release

On July 13, 2007, in celebration of the film's release and the 25th anniversary of Mitchell's first record-setting performance, Mitchell again played and retook the Donkey Kong record with a score of 1,050,200. Inspired to attempt the record because of the movie, a new King of Kong was crowned on February 26, 2010 when Queens NY plastic surgeon Hank Chien surpassed Mitchell's high score by scoring 1,061,700.
On August 7, 2010, Twin Galaxies once again certified Billy Mitchell as the record holder with 1,062,800 points. This coincided with the first induction ceremony for the International Video Game Hall of Fame. Mitchell set the new record playing at the Boomers-Grand Prix Arcade in Dania, Fla. where he played for two hours and forty two minutes before quitting once he topped Chien's score. When asked why he quit early, Mitchell said "Some say I'm being cocky. Some say I'm being lazy. I say, I'm being Billy Mitchell." He also once again set the record in Donkey Kong, Jr but on September 9, 2010 he again lost the title, this time to Mark L. Kiehl.
Steve Wiebe once again regained the world record in September 2010, with a score of 1,064,500. . This was broken by Hank Chien in January 2011, with a score of 1,068,000.