What is the major advantage of a 4-head VCR as opposed to a 2-head model?
Each head is used for either playback or recording. In a 2-head VCR you have one head for recording at all different speeds and one for playback on all different speeds. With a 4-head VCR you have one set of heads for playback and recording at regular speed and one set for playback and recording at slower speeds (giving you more recording time from the same length tape). The result is higher quality recording and playback.