Ipad4 video resize flicker from windows movie-maker

I'm not sure if my problem is with the ipad4. I'm making movies in windows movie-maker with videos taken with my ipad4. After I have saved the movie-makerfile as mpeg4 my videos resize slightly around the outer edge on playback; is like flickering from large to small around the edges; this happens only where one frame ends and another starts. It sounds like a movie-maker issue but the version has not changed and it was ok before. I don't believe I had the issue before the ipad update. My older videos made with movie-maker are all fine with no outer-edge resizing. I have unistalled movie-maker and reinstalled with no change.

My video drivers for xfire are up-to-date

Any help is appreciated.

Graham