Dunham has been called "America's favorite comedian" by "Slate". According to the concert industry publication "Pollstar", he is the top-grossing standup act in North America and among the most successful acts in Europe as well. As of November 2009, he has sold over four million DVDs, an additional $7 million in merchandise sales, and received more than 350 million hits on YouTube as of October 2009; his introduction of Achmed the Dead Terrorist in "Spark of Insanity" was ranked as the ninth most watched YouTube video at the time. "A Very Special Christmas Special" was the most-watched telecast in Comedy Central history, with the DVD selling over 400,000 copies in its first two weeks. "Forbes" ranked Dunham as the third highest-paid comedian in the United States behind Jerry Seinfeld and Chris Rock and reported that he was one of the highest-earning comics from June 2008 to June 2009, earning approximately $30 million during that period. Dunham also does occasional acting roles. He achieved the "Guinness Book of World Records" record for "Most tickets sold for a stand-up comedy tour" for his "Spark of Insanity" tour, performing in 386 venues worldwide.