This function is specific only to the HDMI input that is meant to be connected to a device (like a Blu-Ray DVD player) that outputs 1080p/120Hz. You won't see anything if you are watching regular broadcast. Although the 120Hz function can be turned off, I've read reviews where the reviewer said that this function give the image an almost video-like quality, meaning that it eliminates some of the blur associated with film-based product, but the blur makes a movie look like film rather than video. So, I guess it's a personal preference. If you don't have any plans to buy a Blu-Ray player or PS3 that outputs 1080p/120Hz, then don't worry about it. A good 60Hz TV will still look stunning when properly connected.