''I may have limited intelligence, and limited abilities,'' said Mr. Alpert, who has earned nine Emmies. ''But one thing I do have is that people will let me into places that other people can't get into.'' The results are portraits of lives that are incredibly detailed and therefore convincing in their ugliness: Rob, Freddie and Deliris fall, rise and fall again to drugs, crime, irresponsibility, poverty, cruelty and disease in trajectories devoid of prime-time glamour. Freddie, just out of jail, desperately cruises and sometimes deals heroin. Deliris turns tricks in trucks while her young children wait on the sidewalk. The subjects are white and Latino, which Mr. Alpert said made him less worried about inadvertently perpetuating racial stereotypes and allowed the film to show people of all races making crucial, seemingly inevitable mistakes....