When interviewed during "The Making of Hamlet," about the physicality of this scene where she gets shoved into a wall, Helena Bonham-Carter replied, "Well, then I just have to do some acting."  "Making" showed the construction around this scene, a scaffold used to remove almost all equipment and all lighting, along with some mikes, off the floor of the castle and suspend them above the acting area so that director Franco Zeffirelli could rotate a dolly camera about 270 degrees around Bonham-Carter.  During rehearsal, shown in "Making," Gibson walks around Bonham-Carter with the dolly camera holding one camera operator is pushed and pulled by rope to go nearly around the actress staying opposite Gibson to show his face as he is speaking. 

Why go to this expense and complicate the staging in this way?  Zeffirelli and Gibson acknowledge during "Making" that the director sees this scene as the beginning of Ophelia's loss of sanity, unlike some commentators who see that process beginning when Hamlet accidentally kills her father.