The pop star touched down in NYC Saturday to a lot of fanfare, where she was scheduled for an event amid the film festival in which she'd discuss her 10-minute visual offering of "All Too Well" ... with Dylan O'Brien and Sadie Sink in the lead roles.

TS wrote, directed and starred in the film (not to mention writing/performing the song) ... and Tribeca honchos apparently invited her to discuss it at length during her own window.

Well, that was a damn good idea ... at least based on how many people showed up to see Taylor with their own two eyes. When she pulled up the entrance, a sea of fans were screaming out and trying to snap photos. It might as well have been a Taylor Swift concert.

Once inside, TayTay got serious and started talking vision, direction and execution of her film. She got into the weeds about what different scenes meant, and how she decided to shoot them ... using very film-y terms like "pan," "steady cam" and "protagonist."

She sounds like a regular Scorsese ... and you can tell a lot of thought went into every shot and frame, with Taylor describing the reasons for everything she showed, or didn't.

Later, DOB and Sadie themselves came onstage to delve in even deeper -- and at one point, Dylan started breaking down the themes he intuited, to which Taylor totally agreed.

It's interesting seeing Taylor explore a new creative side to herself -- and considering how well her short was received ... something tells us we'll be seeing a lot more movie magic from her in the future. She's already been cast in a star-studded movie that's in production.