i like so far how the Edain team has striven to make a good balance between the books and the movies, while deferring to the books in points of contention. but this to me is kind of like the Aragorn vs. Sauron battle from Return of the King that was scraped and a troll (Mollok, or "the Sauron troll" as i call him) was placed over Sauron, or Arwen going to Helm's Deep with the Elven army.
i know that, in the Hobbit movies, PJ and Co. rewrote the War in the North and the fall of Minas Ithil in order to have their little "Nazgul tomb" scene. therefore, this could not be the Ithil-stone since, in PJ's world, the Nazgul never besieged Minas Ithil after the fall of Angmar: they just sat in their "tombs" twiddling their thumbs because they couldn't die and the screenwriter ruined the lore!.
however, saying that this is, by some miracle, the Ithil-stone that we see in this scene, it begs one to reason why the White Council didn't take it with them after driving Sauron out of Dol Guldur (we see in the Return of the King movie, when Aragorn looks into the palantir of Minas Anor, Sauron in his armored form holding the Ithil-stone).
in conclusion, this was a potentially problematic scene that PJ and Co. thankfully had the proper sense to abstain from...if only they had the foresight to be as tempered with the other problematic scenes that made it into the final cut