Show current frame or display timecode (frames) on MPC-HC?
If the video file has subtitles (even fake ones, even not being displayed), you can go to View -> Subresync (or hit Ctrl + 6) and you'll see the timecode in the status bar displayed as {Hour:Minute:second.frame}.  As yet, I haven't found how to make this display format permanent, to appear even without a subtitle track.

EDIT:  In my own searching, I just came upon a post elsewhere stating that if you right-click the time on the status bar, in ANY video, whether or not it has subtitles, then you will see an option for "High precision".  You only need to select it once, and then the preference will be remembered for all subsequent files (even audio only).