Run a file through Mediainfo and post a screenshot.
What are your sequence settings,
What are your export settings,
Media Info: http://i.imgur.com/Whfg5BK.jpg
Sequence Settings: http://i.imgur.com/U8cY308.jpg
Export Settings: http://i.imgur.com/rvawe6x.jpg
Like i said, everythings fine in the original files and the preview so not sure whats up with the blur. Must be a setting or codec issue somewhere because i remember Sony Vegas doing the same thing to me in the past.
Mayby the bitrate: 237 vs 40.
I don't normally use a bitrate that high because when i do the rendered file just refuses to play at all. And even with half that, i often have to upload to Youtube at least 2 or 3 times before it processes correctly.