Your link didn't mention they did it under the exact same conditions. Doing it under the exact same conditions is the only thing that matters. Sorry, brother. Your argument fails.
I saw the CBS special when they did the test.
It did replicate the same conditions. There was also another televised such experiment that replicated the conditions under which Oswald was supposedly shooting...it also indicated that it was possible.
Sorry Junior, your argument is based on your limited knowledge of the assassination (I was alive then, have studied it for years, actually have a copy of the Warren Commission Report, etc.), and hero-worship of Carlos Hathcock.
Note: Oswald's rifle practice did not end with his Marine Corps experience. He regularly participated in a rifle club when he lived in the U.S.S.R.
There are a lot of "hinky" things that do not make sense about Oswald being the lone assassin, but that he could not have fired the shots, is a myth.
Far more troubling is the fact that when Oswald was about to be apprehended in the movie theater, one of the detectives told the manager that, "...that is the guy who shot Kennedy...", when at the time, the suspect in the theater was only connected with the shooting of officer Tippet.
Also unexplained, is the police officer who went up the "grassy knoll", and confronted the person putting a gun in to a case in the trunk of a car, who produced a badge and identified himself as "Secret Service". That supposed Secret Service person has never been identified and the Secret Service has always claimed that they did not have any agents on top of the knoll that day.
Such inconsistencies are far more troubling than someone hitting a person at relatively close range with a scoped rifle.