Actually, I am just a MC user like you. So it isn't my software. But I'm sure JRiver appreciate the feedback and thanks.
I see you are using MC22. It is up to MC27 now, and there have been a lot of changes since MC22, and some changes to the Playlist export functionality. It looks like the attached image now. But MC22 should still work for what you want.
0) Best to export a Playlist with this on and then off, and compare the two files. Use the m3u file type. They are just text file, so you can open them in Windows Notepad to have a look at them.
Basically, if you use a NAS and have the location of the media files mapped to the M: drive on the PC, then your music may be in "M:\Music\Enigma\MCMXC A.D\", with a file name such as "01 - The Voice of Enigma.flac". If you didn't turn on the "Store path relative to the export playlist location" setting checked, then the m3u would contain the line:
M:\Music\Enigma\MCMXC A.D\01 - The Voice of Enigma.flac
That would be fine if the second PC or laptop also used the drive letter M: for the NAS, as MC would find the file no problem.
But if the second PC had the NAS drive mapped to the Z: drive, then MC wouldn't find the file, as it would look on the M: drive. Of course, most people map the same drive letter for the NAS on all their PCs, so this doesn't happen. But in this case, the media files would be in "Z:\Music\Enigma\MCMXC A.D\", and the specific file would be found at:
Z:\Music\Enigma\MCMXC A.D\01 - The Voice of Enigma.flac
So if the mapped drive letters were different, and perhaps you exported the playlist to "M:\Music\Playlists\" on the first PC, then turning on the "Store path relative to the export playlist location" setting would see the line in the exported playlist file changed to:
.\..\Enigma\MCMXC A.D\01 - The Voice of Enigma.flac
The .\ tells MC to start looking in the current directory, which is where the exported playlist file is located, which is "M:\Music\Playlists\" on the first PC, and "Z:\Music\Playlists\" on the second PC.
The ..\ tells MC to move up up level in the directory structure, so now it would be looking in "Z:\Music\".
Then MC adds the rest of the path to the file, looks for and finds it at "Z:\Music\Enigma\MCMXC A.D\01 - The Voice of Enigma.flac".
So that is what that setting does. It accounts for different paths to files on different PCs. This is most useful when each PC has all the media files on a local drive, or when sharing Playlists with friends who have completely different setups. But it can be used in the situation above as well.
1) The MPL, HTML, and Text format of exported Playlists just add a lot of metadata about the music file to the exported file. If you are doing what sot13 was doing, and asking the same question, then you don't need to use these. That is, you are running a separate MC Library on two PCs. Now, that isn't the way I would use MC in a home network where I was connecting to a NAS, because I would use the MC Client/Server functionality. But that is a whole different question and would take a long time to explain. In fact, you would have to start learning lots. As a five year old with head injuries, that may be a challenge!
2) The list of Playlist file types that just include the file name. You should use either the Simple or Extended m3u type. The extended just adds a little metadata, Artist and Album, to the file. Not required here.
3) Only used if you select MPL, HTML, or Text file export type. Will be greyed out when you select m3u.
4) If you select "All", then all the files in the Playlist you have selected will be included in the exported Playlist file.
If you select "Selected" then only those files you have selected in the Playlist will be included in the exported Playlist file.
Yes, the Wiki could use a lot of work, in many places. But no-one pays me to do that, JRiver spend most of their time writing software, and only a few other people write Wiki articles for JRiver.