"till, there are a couple of key caveats here. DO NOT buy this TV for gaming. While Amazon lists its hz rate at 120, this is not true for 4K. This display can only output 4K at 30hz which is not zippy enough for most games, but it should be fine for movies. "
TVs usually double the framerate and put black frames between them to increase contrast etc. Of course they only take 30 Hz input, since anything else doesn't make any sense for a TV anyway. TVs aren't just big monitors.