Fortunately all MOV videos making problems with XnView's built-in player do play with XnViewMP's built-in player.

But unfortunately some of my videos rotated from landscape to portrait orientation are not shown correctly by XnViewMP. XnViewMP plays with width 1920 pixel to height 1080 pixel ratio while video should get played with width 1080 pixel to height 1920 pixel ratio. Other players e.g. VLC player and even XnView (without MP) do handle these videos as expected. See short MOV file attached.