A videocassette tape about the 1982 Chicago-area Tylenol killings was found in the home of a 20-year-old man who has admitted attempting to extort $2 million from authorities in the recent New York Tylenol poisonings, it was disclosed in a court hearing today.

However, Carl Vergari, the Westchester County district attorney, said discovery of the tape does not change prosecutors' assessment that the would-be extortionist was not the New York killer but an opportunist trying to make money after the tragedy.

DeWitt Gilmore Jr., author of the $2 million extortion letter, appeared in U.S. District Court here for a bail hearing on an unrelated charge of credit card fraud. A copy of the extortion letter, sent to local police, was found in Gilmore's home last week by Secret Service agents investigating the credit card case.

U.S. Magistrate Joel Tyler denied Gilmore bail in that case. He has not been charged in connection with the letter, in which he claimed responsibility for the death of Diane Elsroth, 23, a Peekskill, N.Y., woman who died Feb. 8 after taking Extra-Strength Tylenol capsules tainted with cyanide.

Polly Alpert, a spokeswoman for Video Publishing House of Novi, Mich., which made the cassette called "The Reselling of Tylenol," said it is sold to universities, corporations and libraries and is based on a CBS News "60 Minutes" segment broadcast in 1982.

Vergari said prosecutors still believe Gilmore's letter was "a bungled attempt to cash in on the Tylenol scare." So far, he added, the investigation by the Federal Bureau of Investigation, Yonkers, N.Y., police and his office has produced "no hard leads."

Owen McClain, deputy police chief of Yonkers, where Elsroth was visiting her boyfriend when she died, said "nothing conclusive" was found on visits Monday to Pennsylvania with the FBI to a Tylenol factory and distribution center.

The Food and Drug Administration said it has tested 270,400 Tylenol capsules collected in Westchester County. Johnson & Johnson, Tylenol's maker, said Monday that it would no longer manufacture the medication in capsule form.

*Elsroth's mother, Felicia, told United Press International today that the decision came "three years too late," and company Chairman James Burke said he wished the capsules had not been returned to the market after 1982. "I wish we had never gone back to marketing these capsules," Burke told WABC-TV.