If the girl in the movie's newsreel had not been Mary Dalton, what would Bigger's feelings toward the scene have been and why? In other words, if the scene had been of any rich white girl frolicking in Florida what would his reaction be?
If the white girl in the movie newsreel had been anyone other than Mary Dalton, Bigger's reaction would have been different. Certainly Jack and Bigger find Mary Dalton and the other girls on the newsreel attractive; they refer to them as "babies" and Mary specifically as a "hot-looking number." However, it is the commentator's narration that identifies Mary Dalton as the daughter of Henry Dalton of Chicago that really grabs Bigger's attention. When the commentator also identifies Jan as Mary's "well-known radical" and "Communist friend," both Jack and Bigger begin to imagine the leverage Bigger might have over the Dalton's for knowing so much about their daughter.
Of course, even more important in this scene is the woman who passes Bigger in the movie theater and later identifies him in court. The prosecutor is able to use this information as evidence that Bigger's murder of Mary was pre-meditated.