As far as I know no display does true 5:5 pulldown to convert 24 fps film to 120 Hz. They do 3:2 pulldown to convert 24 fps to 60 Hz and then interpolate the in-between frames to get to 120 Hz refresh rate.
This is not correct as far as I know and really is very unlikely if you are to analize how film actually looks. There are a few VERY new displays that support frame interpolation at 120hz, which is a feature that can be turned off, and has been considered to look poor.
Let me explain:
Original film based material is shot a 24fps (hz) - that's a given.
BUT - and this is the most overlooked, and very important point...
Film is not shot a 1/1000th of a second per frame, or 1/500 of a second - it uses a slower shutter speed, so that if you pull one frame of film that has motion in it, you will see blurring within the image.
If you put two frames next to each other, both of which have motion, the second frame will pick up the blurring where the first frame left off. This means that shutter speeds run very close to 1/24th of a second and you get that much blurring in every frame.
Durtion motion sequences, on video, this helps to make the motion look smooth - otherwise you would end up with motion that appeared jerky, like under a strobe light. Older video games that didn't blur motion often had complaints about this issue and newer games address this... or speed up motion significantly.
But, for video, to perform tween frame interpolation, the original frame must first be deblurred to compensate for the new frame that will be inserted, which also must contain blur. This requires that multiple frames be pulled into a frame buffer, and they must be compared to frames around them to determine the proper way to de-blur all the motion - which may not all be in the same direction.
So, with 1080p, that's an interpolation of 2,000,000 pixels at 24fps to determine tween frames by deblurring existing frames, and properly blurring and inserting new frames into the video path.
The complexity of the math - and the raw horsepower to accomplish such a feat is staggerring. Good photo editing programs have issues doing this well on a single frame - and it often takes a half second or more to accomplish.
So, you begin to see that the more likely way to interpolate tween frames is to try to find a mid-point. The problem is, this will actually make the video look worse since it doesn't truly maintain the motion flow that was in the original filming and may lead to additional blurring of the video playback.
This is why, tweening of frames is a function that can be disabled in the newest displays that can accomplish it. Instead, you do get a 5:5 sequence where 24fps original material is displayed 5 times in a row, then the next frame is brought up. It is the most accurate representation of the original film material and delivers the theatrical experience to the home without the added influence of a bunch of faked digital frames which don't enhance the original look.
