What does does "QTE" under Witcher 2 settings stand for?
There's an option called "Difficult QTEs" under Options menu of Witcher 2 - What are "QTEs"? What do they do? What is the consequence of enabling/disabling them?
QTE stands for quick time event, also known as "Press X to not die".
[...] a Quick Time Event (QTE) is a method of context-sensitive gameplay in which the player performs actions on the control device shortly after the appearance of an on-screen prompt. It allows for limited control of the game character during cut scenes or cinematic sequences in the game.
The "Difficult QTEs" option controls whether you see quick time events at all during the game. Turning it off removes them entirely, with the exception of the ones involving the fistfighting system.