[CraftyClown]

 Did you figure out a solution for the 1/4 videos? 

If I'm understanding your problem correctly, I think the 1/4 box in the top corner is a windows scaling issue.

Display settings / scale and layout / 100%   seemed to fix it for me. 

Windows scaling is set at 100% . Seems to happen when I have madvr configured to switch refresh rates. If I remove all the display rates and leave the madvr box emtpy it works.

Is that a problem?

What do you mean by Display settings / scale? 

Ah ok, I may be misunderstanding the issue you are having in that case.

I have a 4k TV and my windows 10 box wants to default to 250% scaling. When set like this, occasionally when I finish watching a film or TV show my Kodi interface will scale itself down to a 1080p window and sit in the top corner.

I was referring to the windows display setting options (right click on desktop) however if you are set at 100% then this is clearly not related.