Ok, I just watched the same portion of 300 (a fight scene, chapter 14 I believe) about 20 times or more with various settings. I only used one setting at a time, so I can't speak for any interaction between the three.
CineMotion - Can't tell a difference with any setting. It appears as if it is doing the right thing and turning itself off. I watched all three settings several times over as closely as I could, and could not see any difference at all. It would be interesting to see if I can tell any difference on a standard DVD where Cinemotion should kick in... I'll try that later if I get a chance.
Motion Enhancer - Can't tell any real difference on any setting.
Motion Naturalizer - This certainly inserts black frames, and you can tell it. Auto 2 produced a horrible flicker. Auto1 was better, but still flicker. If you pause the video with either one on, it is immediately very obvious. I will say this, it does kind of give you that feeling that you are watching a film projector, but Auto2 simply over does it. Auto1 might be suitable for some people who really want that movie theater feeling. I wouldn't want to watch it in a completely dark room, but it might be to your liking with some backlighting.
The next part is read at your own risk and may be COMPLETELY wrong
As for all this 3:2 pulldown mess that has everyone confused... it is a very complicated topic because there are more acceptable framerate/resolution/scanning modes than you realize. Whether or not a reverse pulldown is needed or applied, and what cadence it is, is highly dependent on the source. Take a look at this link for the acceptable ATSC standards:http://en.wikipedia.org/wiki/ATSC_Standards
All of the 576 line resolutions are PAL, but the rest are acceptable NTSC/HDTV for the US. You can see how it can become confusing and how complicated the algorithms must be to accurately detect and deal with all of the possibilities.
As for SD DVD's, most of them are soft telecined
. We have to realize that there is a difference betwen a 3:2 pulldown and interlacing
. To get the 3:2 cadence needed to convert 24 fps (film) to 30 fps for NTSC display, we take all the frames and interlace them to create two fields for each frame, with one field containing even scan lines and the other containing odd. If we take two successive frames, A and B, then we start with this on film.
Now let a and b denote the fields for A and B, and E and O denote Even and Odd. After interlacing, we get this:
aEven aOdd bEven bOdd
That is good and well, but it does not fit the 3:2 pattern we need for the math to work correctly. We must do a 3:2 pulldown and repeat a field:
aEven aOdd aOdd bEven bOdd
Now you can immediately see some problems. The last aOdd created from the pulldown will be displayed with bEven as one frame, which gives us interlacing artifacts. This is what we had to live with when all displays were interlaced, 30 fps displays (fps = frames per sec, NOT fields per sec).
Now, since MPEG2 compressors are so smart, they realize that the second aOdd frame is just a repeated frame, and does not need to be included in the video stream (this saves space). Instead, the DVD is encoded with a flag that tells the player to perform the pulldown. All the player does is repeat the aOdd frame when it needs to. So, the information is actually stored on the disc as:
aEven aOdd bEven bOdd
Which is 24 fps, but Interlaced
. Now for film, we can undo the interlacing to an extent, which is where we get Progressive Scan DVD players. They attempt to undo the interlacing for display on a progressive TV, a.k.a almost any HDTV. This is great, but we still must apply the pulldown to get the frame rate right. The interlacing artifacts may be gone (for the most part, it gets complicated), but the judder from the 3:2 pulldown is not.
Now... the holy grail is for a DVD player to recognize the above format and say "hey, what if I just put the fields back together to get the original 24 fps progressive material, just like it was on the film, and display that?" It is now possible for this to happen because sets like the A3000 can actually display the 24 fps if the DVD player puts it back together for us. Then we take the aEven and aOdd fields, put them back together (remember they are from the same original film frame) to get, guess what:
... and the circle of confusion is complete. Currently the only DVD player I know of that will do this is not a DVD player at all, but the new Toshiba A4 HD DVD player. The PS3 is certainly capabable of doing it with a software upgrade.
Now you see why CineMotion is not needed and should turn itself off for 24p input. CineMotion's job is some mixture of attempting to reverse the 3:2 pulldown / deinterlace, but I don't know exactly what it tries to accomplish. It could be trying to get back to the A B scenario above for TV's that have 24p display capabilities. For those that don't, the best it can do is deinterlace and maybe do some type of frame interpolation to smooth out the judder introduced from the 3:2.
Keep in mind that this info only pertains to film material put on DVD. There is a lot of other material that you will find on DVD that is interlaced differently, such as "video" from a camcorder type device. That material is a whole different ballgame entirely.