In some games when record video(any resolution) with 30(vsync off or on, no matter) and less fps(60hz monitor), recorded video stuttering in some areas, but when record with 60fps, everything is smooth .
As an example, recorded me3 video.
1920x1080; 30fps.
1.Action http://www.youtube.com/watch?v=X3n1DIyFXsI , not smooth
2.Fraps http://youtu.be/HmXyeAtPATI , smooth.