[lexiconman]

After doing some more research, I've modified the files as follows. Result is now DSplayer plays for everything. N either VideoPlayer or MPC ever get automatically called.

<playercorefactory>
<players>
<player name="MPC-HC" type="ExternalPlayer" audio="false" video="true">
<filename>C:\Program Files\MPC-HC\mpc-hc64.exe</filename>
<args>"{1}" /fullscreen /close</args>
<hidexbmc>false</hidexbmc>
<hideconsole>false</hideconsole>
<warpcursor>none</warpcursor>
<playcountminimumtime>1140</playcountminimumtime>
</player>
</players>
<rules action="prepend">
<rule filetypes="mkv" player="DSPlayer">
<rule filename=".*PRESHOW.*" player="VideoPlayer" />
<rule filename=".*UHD.HDR.*" player="MPC-HC" />
<rule filename=".*3D.MVC.*" player="MPC-HC" />
<rule filetypes="mp4|mov|mpeg" player="VideoPlayer" />
<rule>
</rules>
</playercorefactory>