The Clip View is the main part of the Movie Clip editor; almost all motion tracking tools are concentrated within the Clip View.
It should be mentioned that the camera solver consists of three quite separate steps:
2D tracking of footage.
Camera intrinsics (focal length, distortion coefficients) specification/estimation/calibration.
Solving camera, scene orientation, and scene reconstruction.
When a clip is loaded a Timeline is shown at bottom of the Preview. It expands over the full area limited by the animation range. You can move the Playhead by dragging with LMB.
The Timeline is composed of the following visual elements:
Blue line: Playhead
Yellow: Motion track
Yellow line: Keyframe
Orange line: Shape keyframe
Purple: Prefetched frames
Light green line: Solve start/end keyframe