For researchers interested in studying humans and human motion, a regular video recording is often the easiest, fastest and cheapest solution to start with. Nowadays, everyone has access to fairly high quality video cameras even in their mobile phones, and the cost of professional-quality video cameras is also within the reach for many researchers.
One of the positive things about video analysis is that it opens for a broad range of analysis techniques, from purely qualitative methods to purely quantitative. For example, having a video recording that can be played back multiple times, and at various speeds, is very useful for visual inspection. And, as we shall see later, even a regular video recording can be used to extract meaningful quantitative motion data. Furthermore, it is also common to use video recordings as a reference when recording motion with sensor-based motion tracking technologies. In such cases, the video recording can be used to help the qualitative interpretation of numerical results.