25i and 50i are the same by my reckoning. 25p is just having the same image on each field - I am not a tech so I am not really qualified to expound on the fine details of the formats but I have worked with field issues since '81 and have managed to get by so far. if I am doing a project for web or domestic I always merge the fields to avoid what you have in your sample pic. for broadcast I try and give interlace as it delivers a smoother motion resolution. if you are worried about the effect of 60hz light flicker when shooting for 50hz delivery I would suggest you field merge those bits that are troublesome. I have a good field merge plugin from Sapphire FX and there are others
the screen grab is as good as it gets - it is just the Media Encoder which, if you have, I am sure you can find the box labeled field order. it might not be available for every codec but I am sure you can explore to find it