To those who have problems with the MiniDV camcorder playback:
Did you ever mix different brands of tapes in the same camcorder? (I'm asking this because not all brands of tapes use the same binders and lubricants on the tape surface.) And digital recording is very sensitive to such small differences in tape formulation.
If you do mix different brands of tape, it is recommended that you clean the camcorder's head(s) before you switch brands of MiniDV tape.