It is very important to get good video for your analysis, if not, ‘Rubbish in equals rubbish out’.
If your image looks dark, blurry or grainy, it is most often a result of the camera quality, camera settings and/or the lighting. The software cannot correct for bad video.
This resource will help you capture better video.
There is also an excellent series of video clips made by the Biomechanics Teaching Team at the Manchester Metropolitan University that can found for public viewing on YouTube at the following locations: