Under the wrench in the Program Monitor you will find resolution settings for playback and pause.
Make sure its set to full.
It's set to full.
When I export the video the quality is also less (exactly like the quality in the playing screenshot) than in the original.
I cannot see your images nor do I know how much you know about video. Screen captures can be huge and progressive. Video timeilines are usually much smaller and can be interlaced. Tell us more aobut the dimensions of the capture and the format of your timeline.
Here are some specs: http://i.imgur.com/OfM3K3n.png
It's 1920 x 1080
The picture is 1680 x 989
I know the picture is too small, but you can see at the paused picture it's already a bit vague. That doesn't concern me. But the thing I'm worried about is that the paused picture is fine for me but when I let my project play the picture just changes. This also happens for movies I import.