The Summarizer uses extra knowledge beyond what's given by the URL you submit. I tried giving it a link to a synopsis of "Terminator 2: Judgment Day" from IMDB. I then copied and pasted the synopsis into a pastebin online content-hosting site, and gave the Summarizer the URL of the pastebin. Both results are impressive but quite different:
When fed https://www.imdb.com/title/tt0103064/plotsummary/?ref_=tt_st... :
Terminator 2: Judgment Day is a 1991 science fiction action film that follows the story of John Connor and his mother Sarah as they attempt to prevent a nuclear war called Judgment Day. The film follows John and Sarah as they are pursued by a T-1000, a liquid metal android sent back in time to kill Sarah. John and Sarah enlist the help of a reprogrammed Terminator to protect them from the T-1000. In the end, John and Sarah manage to destroy the T-1000 and the chip that would have caused Judgment Day. The film ends with John and Sarah embracing, relieved that they have prevented the nuclear war. An interesting aspect of the film is the Terminator's ability to learn and understand human emotions, which is demonstrated when it refuses to kill John's foster parents and when it grasps Sarah's hand in a gesture of understanding.
Versus https://pastebin.com/Bk183Jky :
The movie opens with shots of traffic and children in playgrounds, followed by a flash-forward to Los Angeles in 2029 AD. The survivors of the nuclear fire called the war Judgment Day are fighting against robotic tanks and androids. John Connor and his mother Sarah Connor are on the run from the T-1000, a liquid metal android sent to kill them. They enlist the help of the Terminator, a cyborg sent from the future to protect them. After a series of intense battles, the Terminator and Sarah manage to destroy the T-1000 in a pool of molten metal. However, the Terminator reminds them that there is still one more chip which must be destroyed; it points at its own skull.
Notice that the first summary mentions "1991 science fiction", but none of the words science, fiction, or 1991 are to be found at that URL.