After using AutoFilter to show category heading contents(lets say the sheet has
1000 items, and the filter shows 250), if you then make a change to a field, and
drag the field down to copy contents to the other fields, it does do do that,
but it will also copy to all fields inbetween those cells (not shown in the filter)

Thus is the chosen filter rows were say:
100
101
105
108
110

The copied data will copy itself between 100 & 110, reguardless if you only
meant to copy to the filtered rows

(Have screenshots to illustrate, but dont see how I can attach them)