Mov edited in Wind. Movie Maker and uploaded to youtube problems?

My camera is a Nikon D5100, it creates.mov videos. I'm using a Windows 7 Windows Movie Maker. I have tried several different ways to upload to youtube using the plugin for the movie maker and uploading through the website. I have even tried uploading it HD.
The problem is the video will only upload the first 20 - 30 seconds and there will be times where it comes out very pixilated. Here is an example:
Do I need to convert the movie file? Or will I have to convert it before I edit it? Or do I need a special codec? I really appreciate the time it takes to answer this for me. This is driving me crazy!

For editing mov file, I suggest the AVS Video Editor, maybe video conversion will decrease the video quality

Yes, you can edit it. Clone2Go free converter can do somen basic video edition as well. You can have a look.
- Does Windows 7's Windows Movie Maker support. MOV files?
- How to edit. MOV files in Windows Movie Maker?
- I have nikon d3300. It shoots videos into a mov file. Is there anyway i can change my settings in the camera to not shoot in mov files
- Windows Movie Maker and Nikon D3100?
- Why won't my videos upload to Windows Movie Maker?