What would cause it to leak from the TOP of the nut? And how to fix(02)

What would cause it to leak from the TOP of the nut? And how to fix(02)

Video Screenshot Gallery: Nutcleaning Leaks

Leaking Packing Nut Repairs - 3 Tips to Repair Valve Leaks
This leaks from the top of the nut. What can I do? : Plumbing
What would cause it to leak from the TOP of the nut? And how to fix