This artifact is visible (and audible) when media suffering from hydrolysis or contamination is restricted from moving through the tape path correctly during playback, indicating that the media needs treatment. This may also indicate that the media is suffering from sticky shed syndrome, and playback should be stopped immediately and the tape removed carefully from the VTR.
Can it be fixed?
To address stiction, the tape must be cleaned by hand or using a cleaning machine. It may also require treatment for hydrolysis using a proven method, such as baking or dehydrating.
The stiction artifact is audible in several places in this clip, starting at 00:04. At about 00:11, look for visible signs of stiction in the ferns