Linear distances can be measured if you have an object of known size in the plane of the motion, like a 10' stick. Only the angles in which the plane of the angle is parallel to the film plane of the video can be measured. In 3D videoanalysis we need to videotape from both camcorders simultaneously an object with at least 6 non-coplanar points, like a cube with its 8 corners. As you view the motion you are beginning to see all the various components that contribute to the motion in a sequence relative to time. Time is important.
Timing is the fourth dimension besides the three spatial dimensions.
So get a good understanding of the time component of the motion. The typical video camcorder records frames at a rate of 30 frames per second. SVHS camcorders have a frame rate of 60 frames per second. The videoanalysis software can draw stick figures for you at 30 or 60 frames per seconds. The Ariel Performance Analysis System allows for you to digitize the joints of the body, frame by frame, and will produce good stick figures for you.