The only thing I'm familiar with when it comes to "120Hz" or "240Hz" LCD HDTVs is motion interpolation, where HDTVs look at the previous frame, the upcoming frame, and make up a frame in between those. Some HDTVs used a black frame, and some HDTVs used a frame made up of the previous and next frames. Samsung called it AutoMotion. LG called it TruMotion, and I'm sure the other manufacturers had their own names for the tech. It was very handy for 30fps games, but it used to cause hella input lag. I first started seeing motion interpolation in HDTVs around 2007. But the shiznit
@Zarathustra is talking about is something I am completely unfamiliar with, and don't recall hearing about before.