I would really like to get a clear answer on this myself. I have copied the wiki answer on this:
Target Ratio (PAL Slowdown)
VideoClock also adjusts the clock rate slightly to achieve an "ideal" ratio between the monitor refresh rate and video frame rate. This ensures, for example, that playing a 23.97 fps movie on a 24.0 Hz display will have a perfect 1:1 relationship. This is done by altering the audio clock by the tiny fraction 23.97/24.00. This removes the annoying occasional video stutter that would happen without this adjustment. The tiny audio change is inaudible.
This feature is also useful for PAL content that's 25 fps. When playing 25 fps content on a 24 Hz display, a 1:1 ratio will be achieved.
VideoClock is willing to adjust the clock by up to 5% if it will result in a perfect ratio between the video and monitor rates.
The first part of this answer isn't PAL Speeddown. What is actually happening is that the video is being speeded up slightly to match the frame rate of the display and so is the audio. The fps of the video file will be set at 23.97. The auto display settings changer will select 23/24 to set the graphics card to the right rate. VideoClock will adjust the system clock to make these match.
The second part is what you are referring to which is PAL Speeddown. If this is to work, something has to tell the graphics card to select 24Hz under the right circumstances. As far as I'm aware, this can only happen in two places in MC17, one is by using the Display Settings and the auto display settings changer and the other is by specifying display modes in madVR. If it is the first, the file fps has to be set to 23.97. If you rely on madVR to set your frame rate, I think the value in the stream will be 25Hz so that isn't going to work.
So it seems to me that the only answer is to change the file fps setting to 23.97.
There is the question of TV series sold on DVD. I am not an expert here and would appreciate some confirmation, or otherwise, but I assume these will generally be shot on video cameras which run at 25 fps in the UK. So that means that they need to be played back at this rate.
Nick.