In the previous clips from Batman Joker demonstrates his deadly "smylex" chemical to Gotham city. His weapon here is a drug, which is what Americans were afraid of at the time. Joker has contaminatted Gotham city's shopping world with his chemicals, and no one knows how his chemical works.
Joker has become a representation of the fears of America. In the 1980s, America was afraid of drugs. "In September 1989, a whopping 64 percent of the respondents in the New York Times/CBS News poll said that drug abuse represented the most important problem facing the country" (Goode 1994). Joker's primary weapon in this film is his "smylex" gas, which is a drug.
In the first clip, the reporter tells the audience that two models died of mysterious causes, and that the police think it might have been due to drug use. One of the major contributers to the drug scare in the 1980s was the deaths of two popular young athletes, University of Maryland basketball forward Len Bias and the Cleveland Browns' defensive back Don Rogers, due to a cocaine overdose (Goode 1994). Director Tim Burton put the deaths of the models in the film to mimic the deaths of the two athletes, which shows us how devastating the Joker's acts are on the people of Gotham city.
The previous clips from Batman show how the Joker is a killer, but still maintains some humor. Joker kills a dozen people, but then makes us laugh by writing, “Joker was here,” on a painting of a house. The audience is so busy laughing as the Joker “improves” the paintings to realize that he has killed at least fifty innocent people in the gallery.