EXPLANATION:
The Rocky Horror Picture Show is a "cult" movie. Pre-COVID, during summers some movie theaters would show it at midnight on a Saturday night. Fans of the 1975 movie would come dressed in costumes, etc., and LITERALLY recite the dialog FROM MEMORY along with the characters. AS A GROUP they also would speak back to the characters. That's where the phrase "No sh*t, Sherlock!" originated.
Understand that it's not just one or two fans--MOST of the audience does it. They've seen the movie SO MANY times that they've MEMORIZED the dialog--to a 1 hour 41 minute movie!
Forensic Files was a half-hour show that explains the events in a specific REAL MURDER CASE and goes through the forensic evidence in detail. Often it talks about "the very first time this evidence technique was ever used."
How many times would a person have to WATCH THE SAME EPISODE--ABOUT A MURDER--to be able to recite the narration FROM MEMORY?